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FREDERICK COLLIN 




Class 



Book « &7f 



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COPYRIGHT DEPOSIT. 



THE BOOK OF STARS 



THE BOOK 
OF STARS 



BEING A SIMPLE EXPLANATION OF THE STARS 
AND THEIR USES TO BOY LIFE 



WRITTEN TO CONFORM TO THE TESTS 
OF THE BOY SCOUTS 



BY 

a/fREDERICK COLLINS 

"the book of wibeless"; " THE book of magic," etc. 




FULLY ILLUSTRATED 



D. APPLETON AND COMPANY 

NEW YORK LONDON 

1915 



Q« 



Cormnrt, 1015, nr 
D. AIM'I.'.ioN AND < OMPANT 



• 1 in tli 



-8 1915 



TO THE BURNHAMS 

WITH PLEASANT MEMORIES OF 
MOUNT HAMILTON NIGHTS 



A WORD TO YOU 

The stars are the friends of everyone who knows them. 

If yon have never stood ont in the open and watched the stars 
on a clear night, you have missed the most wonderful sight to 
be seen from this little old mud ball of ours, and my advice to 
you is not to let another night go by without making friends 
with the stars. 

By the stars I mean everything in the far-off sky that we can 
see, and this includes the white-hot points of light we call the 
fixed stars, the blazing sun, the bright planets, the pale, cold 
moon, the fiery comets and the burning meteors. 

All of these things in the sky are so easily ours to look at, to 
enjoy and to use, that we are apt not to take them at their true 
value, just as many of us do not appreciate to the fullest the 
green grass, the trees, the birds and all the other good things 
we have without price. 

You may wonder how you can make any use o£ the stars, 
but there are dozens of ways by which they will serve your pur- 
pose, from finding the north to lighting a fire, and from telling 
the time to sending a signal, and they are all easy to you when 
you know how. 

All the apparatus you need so that you can know the stars is a 
pair of good, sharp eyes, and if you are fitted with these you are 
ready to begin your work in starcraft this very night. 

A great many folks believe that they must have a telescope with 
which to see the stars, and while, of course, a great deal more 
can be seen with a telescope than without one, still it must be 
remembered that the telescope was invented not longer than four 
hundred years ago and that many important discoveries in as- 



viii A WORD TO YOU 

tronomy were made long before the telescope was invented. And, 
by the way, it was a boy who invented the telescope. 

A small telescope, or a pair of field or opera-glasses, will show 
yon many things in the sky which you cannot see with the naked 
eye, and if you have one of these instruments, by all means use 
it. On the other hand, you can get along very well without a 
glass of any kind until you have learned the things that are set 
down in this book. 

To win a merit badge in the organization of Boy Scouts, a boy 
must pass certain tests ; but it is just as necessary for you to 
know the stars as it is for a Boy Scout, and this book is so writ- 
ten that anyone who studies it can pass the Boy Scout tests, 
and there are a few other things in it which everyone should 
know. 

Once that you have an insight into starcraft, you will 
never need to be told again how very interesting and useful the 
stars are, and once that you have mastered the chief points in 
this book, you should make or buy a telescope having a two- or 
three-inch objective and get a little closer to the stars. 

If any questions should come up which you don't understand, 
if you will write to me, I will write to you. 

A. Frederick Collins. 

"The Antlers," Congers, 1ST. Y. 



CONTENTS 

CHAPTER PAGE 

I. How to Find the North Star 1 

II. How to Know the Stars 14 

III. The Sun, the Brightest of All Stars ... 29 

IV. The Planets, the Sun's Kiddies .... 46 
V. Mother Earth, Old Adam's Planet ... 66 

VI. The Moon, the Earth's Daughter .... 89 

VII. Other Things in the Sky 107 

VIII. Seeing the Stars 121 

IX. The Spyglass or Telescope 136 

X. The Time o' Day 151 

XI. The Stars op the Zodiac 166 

XII. Valuable Information . . . . . . 185 

Appendices ........ 193 

Definitions of Some Words and Terms . . 213 

Index 221 



LIST OF ILLUSTRATIONS 



1. — Starboard showing cleats .... 

2. — Cardboard star . . . . 

3. — The North Star and Big Dipper on starboard 

4. — Finding the North Star and the Big Dipper 

5. — Line for sighting the North Star 

6. — The Big Dipper as we see it . 

7. — The Great Bear as the ancients saw it 

8.— The Earth, Pole Star and Dog Star . 

9. — The North Star and Big Dipper in winter 
10. — The North Star and Big Dipper in spring 
11. — The North Star and Big Dipper in summer 
12. — Telling time by the Big Dipper 
13. — Constellation of Cassiopeia 
14. — Cassiopeia as the Arabs saw her 
15. — The Little Dipper or Little Bear 
16. — The Little Dipper made into a Little Bear 
17. — The Great Square of Pegasus . 
18. — Holding the chart of Pegasus overhead 
19. — The Flying Horse of Pegasus . 
20. — Figure of a trapezium 
21. — Constellation of Orion 
22. — Orion the Mighty Hunter . 
23. — Constellation of Auriga . 
24. — Auriga the Shepherd 
25. — Constellation of Taurus . 
26.— Taurus the Bull .... 
27. — Star map showing six chief constellations 
28. — Smoking glasses over candle flame . 
29. — Seeing the sun through smoked glasses 
30. — A candle flame showing layers of flame 
31. — The sun as we see it 

32. — Prominences of the sun compared with the 
33. — Cross section of the sun . 
34. — Sun spot in Photosphere . 



size of the 



xii LIST OF ILLUSTRATIONS 

FIG. 

35. — Barometer tube 

36. — Barometer complete 

37. — Boy focussing burning glass on leaves to make fire 

38. — Boy sending flash signal with mirror 

39. — Continental Morse Code 

40. — Base for heliograph ... 

41. — Back view of heliograph . 

42. — Top view of heliograph 

43. — Side view of heliograph . 

44. — Heliograph complete 

45. — Numbered strip for sundial 

46. — Tin ring for sundial 

47. — Brass semi-circle with shadow wire 

48. — Sundial complete 

49.— To find the North by a watch . 

50. — A star and a planet in a telescope 

51. — Sizes of planets compared 

52. — Three views of Mercury . 

53. — Mars as seen through a telescope 

54. — Three views of Venus 

55.— The earth 

56. — Jupiter 

57. — Saturn 

58. — Uranus 

59. — Neptune . 

60. — Marbles on top of table . 

61. — Top view of solar system 

62. — Solar system in perspective 

63. — Egg shell on plate . 

64. — Boy throwing stone to illustrate centrifugal force 

65. — Iron ball pendulum swinging in straight line 

66. — Iron ball pendulum swinging in curved line 

67. — Map of stars on sun's path .... 

68. — Diagram of position of constellations . 

69. — Plotting position of planet .... 

70. — Cross section of the earth ..... 

71. — Sails of ship can be seen after hull has disappeared 

72. — Sailing round the earth ..... 

73. — The earth moves away from the swinging pendulum 

74. — If the earth 's equator was in a line with the sun . 

75. — The earth tilts on its axis ..... 

76. — Light in room to represent sun .... 

77. — Top spring on plate ...... 



LIST OF ILLUSTRATIONS 



78. — Circle around candle marked with seasons . 

79. — Apple to represent earth suspended in air . 

80. — Position of the earth and sun in autumn . 

81. — Position of the earth and sun in winter 

82. — Position of the earth and sun in spring 

83. — Position of the earth and sun in summer . 

84. — Cycle of seasons ..... 

85. — Lines of force through and around a magnet 

86. — Lines of force around the earth . 

87. — Watch spring needle for compass 

88. — Compass complete ..... 

89. — Pocket watch-case compass 

90. — Dial of mariners ' compass . 

91. — Needle for dipping needle .... 

92. — Dipping needle complete .... 

93. — Protractor showing degrees 

94. — Earth surface divided into degrees 

95. — Protractor set by dipping needle showing latitude 

96. — Two sticks screwed together 

97. — Two sticks across bucket of water . 

98. — Protractor and sticks on drawing paper 

99. — Sextant in use. Shooting the sun 
100. — Shadows at the North Pole 
101. — Moon and earth joined together like a dumbbell 
102. — Balls connected with an elastic . 
103. — Map showing Pacific Ocean 
104. — Imitating the volcanoes in the moon 
105. — Beal volcanoes .... 
106. — Naked-eye drawing of full moon 
107. — Experiment showing how one revolution of the : 

the earth makes it turn once round its axis 
108. — Apple cut to show crescent 
109. — Diagram showing how the moon's phases are made 
110. — Diagram of the moon's phases as we see them 
111. — Boy, lamp and orange showing phases of moon 
112. — Attraction of the moon causes the tides 
113. — How spring tides are formed 
114. — How spring tides are formed . 
115. — How neap tides are formed 
116. — How neap tides are formed 
117. — View of the earth from the moon 
118. — Telling time by the moon . 
119. — Eclipse of the moon by the earth (experiment) 



round 



XIV 



LIST OF ILLUSTRATIONS 



FIG. 

120. — Moon eclipsed by the earth (diagram) 

121. — The moon as seen when in eclipse 

122. — Eclipse of the sun by the moon (experiment) 

123. — The sun eclipsed by the moon (diagram) 

124. — Total eclipse of the sun, showing path of the sun 

125. — Total eclipse of the sun, from photo . 

126. — Annular eclipse of the sun 

127. — Partial eclipse of the sun . 

128. — Comet showing Nucleus, Coma and tail 

129. — An ellipse, parabola and hyperbola 

130. — Head and tail of comet do not obey the same laws 

131. — Halley's comet, from photo 

132. — Meteorite of iron etched with acid 

133.— The Milky Way 

134. — Different forms of nebulas . 

135. — Eipples or waves on water 

136.— Vibration of a bell . 

137. — Sound waves in the air set up by bell 

138. — Waves in the ether . 

139. — Forming an image with a lens 

140. — The human eye 

141. — Light reflected by an apple 

142. — Light reflected. Spoon in glass of water 

143. — How light is reflected 

144. — Prism .... 

145. — Prism forming a spectrum 

146. — Convex lens 

147. — Concave lens 

148. — Lipperhey's boy discovers telescope . 

149. — Disk of cardboard for pinhole telescope 

150. — Cross section of pinhole telescope 

151. — The telescope (Galileo) 

152. — Opera glasses ..... 

153. — Pasteboard mounting of lens . 

154. — Pasteboard lens mounting . 

155. — Opera-glass telescope. Cross section . 

156. — Telescope. Cross section view . 

157. — Magnifying power of telescope . 

158. — Full view of moon .... 

159. — Glass globe cracked .... 

160. — Map of the moon .... 

161. — The moon girl ..... 

162. — Diagram showing how to find solar noon 



LIST OF ILLUSTRATIONS 

FIG. 

163. — Circle divided into 360 degrees and 24 hours 
164. — The earth divided into 24 standard meridians 
165. — Standard time meridians in U. S. 
166. — Standard time at different cities 
167. — Euled glass in transit instrument 

168. — The time ball 

169. — Eeeeiving time signals by wireless 

170. — The zodiac as invented by the ancients 

171. — The zodiac as we know it today 

172. — Constellations and signs of the zodiac 

173. — Cardboard zodiac ..... 

174. — Constellations of zodiac in circle 

175. — Constellations of Aries the Earn 

176. — Constellations of the Lion and Big Dipper 

177. — Constellations of Virgo the Virgin . 

178. — Libra, Lion, Scorpio, Virgo 

179. — Lyra, Aquila, Capricornus .... 

180. — Camera pointing to North Star 

181.— Star trails 

182. — Boy looking through prism at slit in cardboard 
183. — Fraunhofer's lines ..... 
184. — The spectroscope ..... 
185. — Geometrical figures ..... 
186. — Kullmer star finder . . . 



XV 

PAGE 

157 
158 
159 
161 
162 
164 
165 
167 
167 
170 
171 
172 
174 
177 
179 
179 
181 
186 
187 
189 
190 
191 
195 
209 



THE BOOK OF THE STARS 

CHAPTEE I 

HOW TO FIXD THE NORTH STAR 

If you want to know something about the stars which will be 
helpful as well as entertaining, the first thing you should do is 
to be able to find the North Star. 

The North Star is taken as a starting point in the sky for 
two very good reasons : first, of all the thousands of stars which 
the eye can see, it alone never moves ; and second, it is due north 
from any place on the Earth's surface from which it can be seen. 

It must be plain then that this star is the most important 
one of all to us, for by its friendly light we can easily tell the 
points of the compass, though we may be lost in an unknown 
land or shipwrecked on a strange sea. That is, of course, we can 
easily find the points of the compass if we have first learned how 
to find the North Star. 

How to Make a Star Finder.— To find the North Star for 
the first time is a very easy matter if the simple directions given 
below for making and using a star chart, or star finder, are fol- 
lowed. 

Get a smooth pine board, about 16 inches wide, 20 inches 
long and % inch thick ; make two cleats of wood, each of which is 
1 inch wide, 12 inches long and % inch thick, and screw these 
to the board near the ends and on the same side, to prevent the 
board from warping, as shown in Fig. 1. If a drawing board of 
any size is at hand, it will serve the purpose just as well as a 
home-made board. 

The next thing to do is to obtain a sheet of cardboard about 
l 



9, THE BOOK OF THE STARS 

12 by 16 inches and cover one side of it with a dull black paint; 
when the paint is thoroughly dry lay it, black side up, on the 
smooth side of the board. 

From another sheet of white cardboard cut out seven stars, 




Fig. 1. — Starboard Showing Cleats. 

about the size and shape shown in Fig. 2, and cut out another 
star nearly twice as large, to represent the North Star. 

Now place the white stars on the black surface of the card- 
board in the positions shown in Fig. 3, using the smaller stars to 
form the outline of the Big Dipper and 
the large star for the North Star. 

When all of the stars have been 

properly arranged, fasten them to the 

black cardboard with a bit of glue or 

mucilage. Push a thumb tack, or a 

pin, through the center of the large 

star, which is the North Star, and well 

Fig. 2. — Cardboard into the board, so that the chart, or star 

Star. map, can be turned round on the board 

with the North Star as its axis. When 

this is done your star finder is complete. 

Finding the North Star.— All being in readiness, take this 
chart, or star finder, out of doors some evening when the seeing 
is good and all the stars in the northern sky are shining brightly, 
and face about north, holding the starboard in front of you, as 
shown in Fig. 4. 




HOW TO FIND THE NORTH STAR 



S 



Usually the direction of north is well known, and yet there 
are some places where the streets and roads do not run due north 
and south, and for this reason it is sometimes hard to tell exactly 
which way is north. In such a place either use a compass to get 
your bearing, or, if you haven't a compass, face about as nearly 
north as you know how. 





TOP OR NORTH y^ 


PIN 


NORTH T STAR 


UJ 




So 

< 


BOTTOM OR SOUTH 



Fig. 3. — The North Star and Big Dipper on Starboard. 
(Position of Big Dipper in Autumn.) 

Having looked at your star chart carefully raise your eyes 
from the board until they are in a line with the northern horizon, 
that is, the line where the earth and the sky seem to meet. Keep 
on raising your eyes in a straight line until they reach a group 
of stars, which is about 40 degrees above the horizon. (See Fig. 
98.) The line for sighting the North Star is shown in Fig. 5. 

All the stars of this group are very faint except one and this 
particular star will stand out bright, distinct and alone, for the 



4 THE BOOK OF THE STARS 

other two stars of the same group which can be plainly seen 
are not very close to it. The star you have found is the North 
Star, or Pole Star, or to give it its proper name Polaris (pro- 
nounced Po-la'-ris). 






,/ 



* NORTH STAR IN 5KY 







Fig. 4. — Finding the North Star and the Big Dipper. 



To make sure you have not mistaken some other star for 
the North Star it will be a good idea to prove your find. To do 
this turn your eyes to the left a little and you will see a group of 
seven bright stars fixed in the sky just as the cardboard stars are 
fixed on the black surface of your chart, and which are shown in 
Figs. 4 and 5. 

The Big Dipper. — This group of seven stars is called the 
Big Dipper because if a broken line joined all the stars together 



HOW TO FIND THE NORTH STAR 5 

a very good figure of a big dipper would be formed. A group of 
stars is called a constellation, and this constellation is shown as 
we see it in Fig. 6, and as the ancient shepherds and sailors 
pictured it in Fig. 7. 

* NORTH STAR 



\ HORIZON 




Fig. 5. — Line for Sighting the North Star. 



In England this group of stars, or constellation, is sometimes 
called the Plough, for our friends across the pond see in it the 
likeness of a plough as well as of a dipper. It is also called the 
Great Bear the world over after the ancient name given it, but it 
requires some stretch of the imagination to liken it to that 
nubbly short-tailed animal. 

All these fancy names were given this great group of stars 
long before the birth of Christ and by these names the constella- 
tion is still familiarly called. Astronomers of the present time 



6 THE BOOK OF THE STARS 

also call this constellation the Great Bear, but they say it in 
Latin and so it becomes Ursa Major, which is a very high toned 
and scholastic sounding word. But the Big Dipper is a name 
that is good enough for all ordinary purposes and so we'll use it. 




«_* 



Fig. 6. — The Big Dipper As We See It. 

The stars forming the Big Dipper stand out so bright and 
clear in the northern sky that you won't have the slightest trouble 
in finding it, especially if you have the star finder at hand to 
help you. 

In using the star finder there is one thing you should keep 




Fig. 7. — The Great Bear as the Ancients Saw It. 

well in mind and that is that the Big Dipper as we see it turns 
round the North Star, like the hands of a clock, but in the oppo- 
site direction. That is, the Big Dipper seems to turn round the 
North Star from left to right. 

In a word the North Star forms one end of the axis round 
which not only the Big Dipper but the whole starry heavens 



HOW TO FIND THE NORTH STAR 7 

seem to revolve as though they were fastened to the spokes of a 
great wheel. This is the way it seems to us. As a matter of 
fact, though, all the stars are fixed in their positions in the sky, 




or 



NORTH 



POLE STAR 



WEST 




EAST 



SOUTH POLE 



G> 



THE EARTH TURNS 
IN THIS DIRECTION 

Fig. 8. — The Earth, Pole Star and Dog Star. 



and the reason they seem to revolve round the North Star is be- 
cause the Earth from which we see the stars turns round in- 
stead. 



8 THE BOOK OF THE STARS 

By looking at the drawing shown in Fig. 8, it will be seen 
that the north pole of our Earth is directly under the North Star, 
— hence the name Pole Star — and that if we could draw a line 
through the center of the Earth from the south pole to the north 
pole and extend the line far enough, or produce it as it is called, 
it would finally meet the North Star. 

Let us take, now, another star, called the Dog Star — its real 
name is Sirius (pronounced Sir'-i-us) — and which is almost on a 
line with and overhead of the Earth's equator; suppose we are 
some place on the earth where we can see both the North Star 
and the Dog Star at the same time, and keeping in mind that 
the Earth is turning round on its axis; it must be plain, then, 
that though both of these stars are fixed in the sky and never 
change their positions we on the Earth will move away from the 
Dog Star until the Earth has turned half way round, but we 
will not move away from the North Star. 

The eye, however, is easily deceived; for example, if we are 
on a moving train nearby objects, such as houses, trees, etc., will 
seem to be moving in the opposite direction to which we are go- 
ing while we seem to be standing perfectly still. The illusion is 
much more complete when we are seeing the stars, for the mo- 
tion of the Earth as it spins on its axis and shoots round the 
Sun in its orbit is so steady that we cannot notice it; for this 
reason it seems as if it is the stars which are moving and that we 
are standing still. 

It is easy to understand now why the Big Dipper, and all the 
other stars, seem to move in great circles round the North Star 
as well as why the Big Dipper marked with cardboard stars on 
your chart may not have the same relative position to the North 
Star as the Big Dipper of real stars in the northern sky, when 
you view them together as in Fig. 4. 

Not only does the revolution of the Earth on its own axis 
once in every 24 hours cause the Big Dipper to seem to turn 
round the North Star, but the yearly journey of the Earth round 
the Sun makes a change in the position of the Big Dipper as we 
see it at different seasons of the year. And what has been said 



HOW TO FIND THE NORTH STAR 9 

about the Big Dipper is just as true of all the other constella- 
tions. 

For these reasons we would need an almanac to help us keep 
track of the exact hour when the Big Dipper would be in a 
given position for every night in the year. But you can always 
find the Big Dipper any evening in autumn about nine o'clock, 
by remembering that it is turned right side up as shown in Figs. 
3 and 4. Again, if you look for the Big Dipper in winter at 



TOP OR NORTH 



WEST 



BOTTOM OR. SOUTH 




Fig. 9. — The North Star and Big Dipper in Winter. 

about nine o'clock in the evening you will find it standing on its 
handle a little to the east as in Fig. 9. In spring about 9 o'clock, 
it will have moved on round the North Star until it is upside 
down, as in Fig. 10, while in summer, at 9, it is hung up by its 
handle high in the sky, as shown in Fig. 11. The four positions of 
the Big Dipper during the same hours of the different seasons 
are shown in Fig. 12, which also shows the four positions of the 
Big Dipper during each 24 hours. 

By turning the chart round on the board from left to right 
you will soon come to a point where the Big Dipper of paper 



10 THE BOOK OF THE STARS 

stars and the Big Dipper of real stars are in exactly the same 
position. 

You have, no doubt, noticed that a line joins the two end 
stars of the Big Dipper and the North Star in Figs. 3, 4, 10, and 



TOP OR NORTH 




WEST 



BOTTOM OR SOUTH 



Fig. 10. — The North Star and Big Dipper in Spring. 

11. These two end stars of the Big Dipper are called pointer 
stars, for they point directly to the North Star; that is 
if we draw a line with the eye through the pointer stars and 
produce, or continue the line, it will run into the North Star, 
nearly. 



HOW TO FIND THE NORTH STAR 



11 



By using these pointer stars it is easy for any one who knows 
the Big Dipper to be able to find the North Star on any clear 
night in the year, for the Big Dipper can be seen the year round. 

The seven stars which form the Big Dipper are not the bright- 
est stars in the sky by any means, yet each one is a great white 
sun as large or larger than our own Sun. 




Fig. 11. — The North Star and Big Dipper in Summer. 



Now look sharply at the middle star in the handle of the 
Big Dipper, whose name is Mizar (pronounced Me'-zar), and 
see if you can make out another little star whose name is Alcor 
(pronounced Al'-cor) hugging up close to it. The Arabs who 
named them called these two stars the Horse and its Rider. 
If you can see this little star Alcor you will have cause to shake 



12 



THE BOOK OF THE STARS 



hands with yourself, for if your eyes are good you can see it 
and if they are only fair to middling you cannot see it. This 
is one of the famous Arab tests for eyesight. 

How to Tell Time by the Big Dipper. — We have seen how 
the Big Dipper seems to turn round the North Star and this be- 

TOP 
2ATH HOUR 




I8™H0UR 
EAST 



* 



12™ HOUR. 
NORTH HORIZON 



Fig. 12. — Telling Time by the Big Dipper. 



ing the case we can use the pointer stars for the hour hand of a 
big star clock. 

You must always bear in mind, though, that while the 
hands of a clock turn from right to left, the Big Dipper swings 
round from left to right; and there is another thing to be kept 
in mind and that is while the hour hand of a clock goes twice 
round in 24 hours, the Big Dipper revolves only once in 24 
hours, and for this reason the hand formed by the pointer stars 



HOW TO FIND THE NORTH STAR 13 

of the Big Dipper moves only half as fast as the hour hand of 
a watch or clock. 

Each quarter of the circle, then, is equal to 6 hours and 
by dividing the quarter circles into 6 equal parts you can mark 
off the hours. The best way to do this at first is to make a large 
drawing of Fig. 12 on your starboard and compare it with the 
Big Dipper; then draw an imaginary circle round the North 
Star in the sky so that it will just clear the last star in the 
handle of the Big Dipper. With some practice you will be able 
to tell the time within half an hour or less. 

In telling the time by the Big Dipper you must remember 
that the stars in turning round the north pole run fast an 
hour every 15 days, and this makes them gain 6 hours in 3 
months and so they gain a complete revolution in a year. But 
every time the Big Dipper makes one complete turn round the 
North Star, one complete day, as measured by star time, will 
have passed. 



CHAPTEK II 
HOW TO KNOW THE STARS 

One of the tests a Boy Scout must pass in order to obtain 
his badge of merit for starcraft is to be able to name and point 
out twelve principal constellations, and every boy, whether he is 
a scout or not, should be able to do the same thing for his own 
good. 

The word constellation is formed from two Latin words, 
the first being con which means together, and the last being 
stella which means star, or in plain English, constellation means 
stars together. 

In your efforts to find the North Star you have already 
learned one of the principal constellations — that of the Big 
Dipper — and to learn more of them will be even easier and 
much more fun, for now you have learned the game. 

The Constellation of Cassiopeia. — To find the constellation 
of Cassiopeia (pronounced Cas'-i-o-pe'-ah) again make use of 
your star finder. Eemove all the stars from the blackened card- 
board and rearrange them so that the North Star is in the cen- 
ter of the board and the Big Dipper is on the left-hand side 
with the two pointer stars in a line with the North Star. On 
this chart the Big Dipper must be made much smaller than the 
one described in the first chapter. 

Cut out five more stars from white cardboard and place them 
on the opposite side of the board from the Big Dipper in such 
a manner that they will form the letter W being careful to 
fasten the stars to the cardboard so that the letter W stands in 
the exact position shown in Fig. 13. 

A line drawn through the pointers of the Big Dipper and 
produced will, as before, pass through the North Star, and if it 

14 



HOW TO KNOW THE STARS 



15 



is extended an equal distance beyond it, will pass very closely to 
the constellation of Cassiopeia ; this line will aid you in placing 
the stars on your chart in the right positions. 

Having thus prepared the star finder, take it out into the 
open when night conies on and begin by locating the North Star 
and the Big Dipper. Now set the Big Dipper and the North 
Star of your star chart in a position which to your eye corre- 




NORTH 



EAST 



NORTH STAR. 



SOUTH 




Fig. 13. — Constellation op Cassiopeia. 



sponds to the Big Dipper and the North Star in the sky. Fol- 
low the line from the pointer stars to the North Star and be- 
yond when the great letter W which is the constellation of Cas- 
siopeia, will stand out so clear and bright that you will wonder 
why you have never seen it before. 

Fig. 14 shows this group of stars and the outline of the 
unhappy Cassiopeia who is as often standing on her head as on 
her feet, but it requires the imagination of an Arabian star- 
gazer to see the likeness. 

The Little Dipper. — Although some of the stars which. 



16 



THE BOOK OF THE STARS 



form the Little Dipper are very faint it is included in our list 
of 12 principal constellations for two reasons: first, because it 

contains the very im- 
portant North Star, 
and second, because it 
is easy to find. 

The North Star is 
the last star in the 
handle of the Little 
Dipper. The two outer 
stars which form the 
bowl of the Little Dip- 
per, and which are 
called the Guardians of 
the Pole, are quite 
bright, and after a few 
trials you can easily 
put in the stars that are too dim to be seen, and so complete in 
your mind's eye the outline of the Little Dipper as you have it 
on your chart. Fig. 15 shows the arrangement of the stars in 




Fig. 14. — Cassiopeia as the Arabs Saw 
Her. 




Fig. 15. — The Little Dipper or Little Bear. 



HOW TO KNOW THE STARS 



17 



the Little Dipper and the relative position of the Little Dipper 
to the Big Dipper. 

The Little Dipper is also called the Little Bear and this 
latter name when done into Latin becomes Ursa Minor, which 
is its scientific name. How the Little Dipper was made into a 
Little Bear by the ancients is shown in Fig. 16. 

The Great Square of Pegasus. — Unlike the Big Dipper, 
the Little Dipper and Cassiopeia, which are so close to the 
North Star that they 
never set and hence can 
be seen at any hour of 
the night and at any 
season of the year, we 
now come to some con- 
stellations which are 
quite distant from the 
North Star and are for 
this reason to be seen 
only at certain times of 
the year. The Great 
Square of Pegasus can 
always be seen on clear, 
months. 

To find a constellation that is as far away from the North 
Star as Pegasus (pronounced Peg'-a-sus) is not an easy thing 
to do, at least the first time you try it, for while our chart is 
marked with a straight line the sky is like a great bowl and a 
line produced from the North Star to Pegasus will, in conse- 
quence, not be a straight line, but a curved line. However, with 
your star finder charted like the diagram shown in Fig. 17 you 
will be able to locate Pegasus with very little effort. 

After taking off all the stars from the cardboard surface, pin 
or paste the North Star to the lower left hand corner of the 
black surface of the cardboard and place the five stars of Cas- 
siopeia in their proper positions. Now draw a line from the 
North Star through Cassiopeia just below the star marked ft 




Fig. 16. — The Little Dipper Made 
a Little Bear. 



crisp nights during the autumn 



18 



THE BOOK OF THE STARS 



which is the Greek letter beta (see Appendix C) and produce, 
or extend that line until the edge of the cardboard is reached. 
On the extreme right hand end of this line set two stars, which 

we will also call point- 
er stars, and place two 
more stars above them 
so that a nearly perfect 
square will be formed 
as shown in Fig. 17. 

To find Pegasus 
take the star chart out- 
of-doors, say some even- 
ing in September about 
9 o'clock, for the Great 
Square will then be on 
the meridian, that is, 
on a line directly over 
your head and which 
runs north and south 
across the sky. This 
time, instead of look- 
ing down on the chart, 
as you did in finding 
the Big Dipper and 
Cassiopeia, turn the 
board bottom side up, 
as shown in Fig. 18, 
but still keeping the 
cardboard North Star 
pointing north and the four stars of Pegasus pointing toward 
the south. 

By looking over your chart into the sky and following an 
imaginary line with your eye from the North Star through Cas- 
siopeia past the star ft (beta) and lengthening this line toward 
the equator in the southern sky you will come upon four 
bright, white stars which form the Great Square of Pegasus, 



* 


-t 

> 

K EAST 

32 % 

l 

m 


1 

o 

TO 
M 

ZL ■ 

l 

THISISWEST* 
WHEN CHART 

15 HElD 
OVERHEAD 

m -O m \ 

o o 5 <n \ 

> -n > 7* \ 
C m >, 1 

____y±———^ — w 


^£k?S tur 

^A/ CHART 


NTHlSW 1 
15 H£LD ° n 



Fig. 17. — The Great Square op Pegasus. 



HOW TO KNOW THE STARS 



19 



and you have added another and fourth constellation to your 
list. 

The practical value of knowing the mighty constellation of 
Pegasus is that you can always find the north, by means of its 
friendly stars, though the North Star, the Big and Little Dip- 
pers and Cassiopeia are hidden by clouds. To find the north 



NORTH 



WEST 




EAST 



Fig. 18. — Holding the Chart op Pegasus Overhead. 



you only have to run an imaginary line through the pointer 
stars of Pegasus and produce it until it reaches the northern 
horizon. 

The Great Square of Pegasus was fancifully pictured by the 
ancients as a Flying Horse and, curiously enough, with only half 
a body at that, as shown in Fig. 19. To those who do not know 
the lore of the stars it is not so easy to see in the Great Square 
the fabled winged steed who still continues his flight through 



20 



THE BOOK OF THE STARS 




Fig. 19. — The Flying Horse of Pegasus. 



the sky just as he did when he was invented over four thousand 
years ago. 




Fig. 20. — Figure of a Trapezium. 

The Mighty Orion. — The brightest constellation in the 
whole sky is Orion (pronounced 0-ri'-on) ? the Great Hunter, 
as the ancients liked to imagine this group of stars. 



HOW TO KNOW THE STARS 21 

With the exception of the Big Dipper, Orion is the easiest 
of all the constellations to find provided yon look for it at the 
right time of the year, which is during the winter months. 

To locate Orion cut out of cardboard seven large stars and 




Fig. 21. — Constellation of Orion. 

three small stars. Near the lower edge of the blackened card- 
board pin two large and two small stars to form what is called 
a trapezium, that is, four straight lines forming a figure, none 
of which are parallel, as shown in Fig. 20. About halfway 
across the figure pin three large stars in a row, at equal dis- 
tances apart and tilted a little, as shown in Fig. 21. 

These three stars form the Belt of Orion, for a mighty 
hunter must needs have a belt, and this belt of bright stars is 



g£ THE BOOK OF THE STARS 

one of the best known groups in the whole sky. Across the belt 
and nearly at right angles to it pin three small stars; these 
small stars form the sword or dagger of the fanciful hunter but 
they are of more use to us than to him, as will be seen presently. 
At the top of the star chart pin the North Star so that it 
will be in a direct line with the three small stars forming the 
Sword of Orion. Your star chart of Orion is now ready to be 
compared with the one in the sky. The best time to find Orion 




Fig. 22. — Orion the Mighty Hunter. 

is in November about 9 o'clock, when the constellation is high 
in the southern sky, though he may be seen shining in all his 
glory all winter long. 

On taking your star chart out-of-doors hold it overhead just 
as you did in finding the Great Square of Pegasus; now look 
toward the south until your eyes rest on the equator running 
across the southern sky from east to west and you will see the 
mighty Orion, though you may not recognize the lion skin he 
holds. 

Having found Orion draw an imaginary line through the 
three small stars called his sword and produce this line until it 



HOW TO KNOW THE STARS 23 

meets the North Star. Once you have found Orion you will 
never again require the help of a star chart to locate him, but 
it is a good plan to look him up as often as you can, and to 
draw the imaginary line through his sword and on to the North 
Star, for should you ever lose your way or want to find the 



*— * 



WHEN CHART 
15 H-E.LO OVERHEAD 



THE CONSTELLATION OF AUR.IGA 
(THE GOAT) 



Fig. 23. — Constellation op Auriga. 

north and the North Star should be hidden by clouds a line 
through the Sword of Orion will direct you as certainly as the 
needle of a compass. Fig. 22 shows the fabulous Orion as a 
giant hunter holding the skin of a lion which he killed, accord- 
ing to Arabian star lore. 

Auriga, the Charioteer or Shepherd. — After finding Orion 
the constellation of Auriga (pronounced Aw-re'-ga) will get 



24 



THE BOOK OF THE STARS 



right in your way so that you cannot by any chance miss it. 
This is because the chief star in Auriga and whose name is 
Capella (pronounced Ca-pel'-la) lies nearly on the line drawn 
through the Sword of Orion and produced to the North Star 
as shown in Figs. 21, 23 and 27. 

Auriga was pictured by the Assyrians as a charioteer, but 
the early Greeks saw in this constellation a good shepherd, who 
carried a goat on his back and two kids in his arms. The bril- 




Fig. 24. — Auriga the Shepherd. 



liant star Capella is supposed to be the goat and the three small 
stars which form a triangle close to Capella are the kids as 
shown in Fig. 24. 

When the North Star cannot be seen the star Capella will 
prove a useful aid with Orion in finding the north; and since 
it is just about half way between Orion and the North Star it 
may again be useful in judging the distance of the North Star 
from Orion when the former star is obscured. 

The Constellation of Taurus. — The last constellation which 
need concern us here is Taurus (pronounced To'-rus) the Bull. 
Taurus is one of the constellations of the zodiac of which we 



NOR.TM 



WEST EAST 



CAPELLA 



ALDE3ARAN^ 
TAURUS 
(THE BULL) 



Fig. 25. — Constellation of Taurus. 



25 



26 



THE BOOK OF THE STARS 



will have something to say in Chapter XI. By the time you 
have learned the foregoing constellations you will be able to 
locate Taurus without using your star chart, for it lies to the 
north of Orion, to the south of Auriga and a little to the west 
of both of these constellations as you will see in Figs. 25 and 27. 
The little group of stars nearby is the Pleiades (pronounced 
plai'-e-dez), and is a part of the constellation of Taurus. 



\V^"4 






v^ \VJJ*P 


h 


X 




IN 


< 





Fig. 26. — Taurus the Bull. 



There are six small but bright stars grouped closely together 
when seen by the ordinary person, but if you have very sharp 
eyes you may be able to make out one or two more. 

It is believed that the stars of Taurus were the first to be 
woven into a group or constellation by the ancients, and it is 
thought that the Bull of Light, as Taurus was called, was 
known long before the time of Abraham, or over four thousand 
years ago. Fig. 26 shows Taurus as the Egyptians saw him. 
The bright red star which sets in the right eye of Taurus is 
called Aldebaran (pronounced Al-deb'-a-ran) and is the third 



HOW TO KNOW THE STARS 



n 



brightest star in the sky. In the star chart shown in Fig. 27 
the different constellations you have learned are grouped to- 
gether in the same positions in which they are placed in the sky. 

arcturus 

*. IN 

BOOTES 



£*J 



$&* 



6Ta 



PTJC 



5 bete; 



(THE DOG STAR) 




RIGEL 

SOUTH: 
Fig. 27. — Star Map Showing Six Chief Constellations. 



Six stars of the first magnitude, that is 6 of the 20 stars 
which shine the brightest (see Appendices F and G), are also 
shown on the chart, Fig. 27. By following the equator from 



28 THE BOOK OF THE STARS 

west to east across the bowl of the sky, and which runs right 
through the middle of Orion, you will find to the west and south 
of it the brightest star in the heavens — Sirius, the Dog Star, 
so named because it is in the constellation of Canis Major, which 
is Latin for Big Dog. 

Capella in Auriga is the third brightest star, and Arcturus 
(pronounced Arc-tu'-rus) which can be found by following the 
handle of the Big Dipper, is fourth in brilliancy. The fifth 
place is held by Rigel (pronounced Rai'-gel) in Orion; Aldebaran 
in Taurus is sixth in order, and Betelgeux (pronounced Bet-el- 
gerz') in Orion comes last. 

There are many other constellations and a large number of 
other stars but when you are able to name and point out those 
described in this chapter you will have made a very good run- 
ning start. 



CHAPTEE III 



THE SUN, THE BRIGHTEST OF ALL STARS 



In naming over the stars of the first magnitude — that is, 
the stars that shine the brightest — there is one star I did not 
mention and yet as we see it it is brighter than all the other 
stars put together. 

This great star is our Sun and since we owe everything we 
possess on Earth to him — light, heat, power and even life itself 
— he should and does stand in a class by himself, though after 
all he is just as much of a fixed star as the North Star, the 
Dog Star, or any of the thou- 
sands of other stars which we see 
as mere points of light in the sky. 

How to See the Sun. — Yon 
must never look directly at the 
Sun with the naked eye, for he 
is so powerful that his light will 
injure your sight for all time. 

There are several ways, 
though, to observe the Sun with- 
out danger to your eyes and as 
all of these are simple and cost 
nothing you can easily try them. 
The most common way is to take 
a bit of window glass, say an inch square, and smoke one side 
of it over the flame of a candle, as shown in Fig. 28. 

When this blackened glass is held closely to the eye, as shown 
in Fig. 29, and the latter is directed toward the Sun, a little 
circle of light will appear on the film of smoke and the surface 

29 




Fig. 28. — Smoking Glasses 
over Candle Flame. 



30 



THE BOOK OF THE STARS 



of the Sun may be examined at length and without the least 
danger. 

A decided improvement over the smoked glass idea is to 
use a piece of red, or a piece of yellow glass, as an eyepiece, or, 
better, place the red and yellow glasses together and bind the 

edges with paper. An- 
other plan to see the Sun 
without injury to the eyes 
is to make a hole with the 
point of a needle in a 
visiting card and look 
through the hole directly 
at the Sun. 

A still better view of 
the Sun can be obtained 
if a pinhole telescope is 
used. A telescope of this 
kind can be easily made 
without tools, metals or 
lenses. It is described 
and pictured in Chapter 
IX. 
To observe the Sun hold the pinhole end of the tube closely 
to your eye, to cut off all the outside light, and sight the tube 
so that the Sun shines directly into your eye through the pin- 
hole, and you will get a very brilliant view of the great yellow 
star which we call the Sun. 

What the Sun is Made of. — When a candle is lit the wax 
of which it is made begins to melt and this is drawn up the 
wick where it is changed into gas and the burning gas forms 
the flame. 

The flame of a candle is made up of four parts, which are 
really layers of heated gas surrounding the wick, as shown in 
Fig. 30. In the center of the flame is the wick; the first layer 
of gas is at the bottom of the flame and this gives a greenish- 
blue light; the second layer is the dark and cool part of the 




Fig. 29. — Seeing the Sun through- 
Smoked Glasses. 



THE SUN, BRIGHTEST OF ALL STARS 31 



made of and we 



flame; the third layer is a cone of heated gas which gives out 
the bright light, and surrounding this cone is a faint blue 
light which can just be seen. 

We know, of course, what the candle 
also know why it burns and in a way how 
it gives off light and heat because we have 
examined it closely, but if we could get 
no nearer a candle flame than a quarter 
of a mile it is very doubtful if we could 
ever be able to learn anything about the 
real source of the flame — that is its 
greasy wick. 

It is much the same with the Sun, for 
we can only examine it at a great dis- 
tance and know it by its action on our 
senses, for the flaming layers of the Sun 
are so bright that no one ever saw through 
them, so the real source of its light and 
heat — the core of the Sun — remains un- 
known. Fig. 31 shows the Sun as we see 
him. 

Since the Sun gives out light and heat 
it is easy to believe that it is a great ball of burning gases and 
from what astronomers have learned of him with their wonder- 
ful instruments this idea seems to be pretty well founded. 

The Sun must be a tremendously hot body — f or the iron 
and other metals in it are not only melted but they boil away 
like water and are changed into gases. Under certain conditions 
gigantic flames, called prominences, shown in Fig. 32, can be 
seen to leap from the edge, or limb, as it is called, of the Sun, 
and finally, great holes, called sun spots, are formed on the Sun 
that are so large a dozen worlds the size of our Earth could be 
dropped into any one of them and rattled around like marbles 
in a cigar box. These are a few of the reasons we are led to 
believe that the Sun is a seething ball of fire. 

The Sun's Layers of Flame.— -Just as the wick of a candle 



s fe 


£ A 3 




S-^. /l\ x 


£ jfAl j§ 


* /At * 


<* ihW 


< //Ml w 

o ffflll 3 


1 I VI } CO 


it. 


Ml 




Ill 


Q 




-J 






a 






z— 






< 






u 







Fig. 30. — A Candle 
Flame Showing 
Layers of Flame. 



32 



THE BOOK OF THE STARS 



is surrounded with several kinds of flame, so the Sun has three 
layers of flame around a central core. 

The core of the Sun is believed to be formed of liquid gases 
which are about as thick as New Orleans molasses. 

Around this core, which is the real source of the Sun's light 
and heat — and which has never been seen — is a dark layer of 
flame usually called the Sun's surface; this layer, which is cov- 




Fig. 31.— The Sun as We See It. 



ered with numerous dark spots like freckles on the face of a 
red-headed boy, is called the photosphere, and it is this part of 
the Sun which gives out the most light. 

The second layer, which is called the chromosphere, is about 
5,000 miles thick, and if you could imagine the whole world 
afire you would then have but a faint idea of what a mighty 
seething sea of flame this layer is. It is in this layer of burning 
gases that terrific explosions take place and red tongues of 
flame, or prominences, are shot out for upwards of 300,000 
miles. 

Around the chromosphere is another layer of flame which 



THE SUN, BRIGHTEST OF ALL STARS 33 

extends for hundreds of thousands of miles in all directions. 
This last layer is called the corona, and it is as thin as the stuff 
of which dreams are made. It is formed of burning hydrogen 
and since it is so thin it can never be seen except when there is 
a total eclipse, that is when the Moon passes between us and 




the Sun, which will be explained in Chapter VII, and so shuts 
out the intense light of the other two layers. A cross section 
of the Sun is shown in Fig. 33. 

Sun Spots and Their Effect on the Earth. — Very often 
great spots are seen on the Sun's surface. These purplish black 
spots appear to be holes, like the craters of volcanoes, in the 
photosphere, or layer of flame next to the core of the Sun. The 
sun spots are caused by great eruptions which take place in the 
core of the Sun, and these sun spots, or holes, are sometimes 



34 THE BOOK OF THE STARS 

over 100,000 miles in diameter, when they can be easily seen 
with the naked eye ; indeed if a sun spot has a diameter only as 
large as that of our Earth, it can be seen with the naked eye, 
protected, of course, with either a smoked or a colored glass, or 
better, with a pinhole telescope; in any case it will look like a 




FIRST LAYER; 
THE PHOTOSPHERE 

SECOND LAYER; 
THE CHROMOSPHERE, 



THIRD LAYER; 
k THE CORONA 



Fig. 33. — Cross Section of the Sun. 

black speck about the size of a pinhead. Fig. 34 shows a view 
of a sun spot made through a large telescope. 

Whenever the sun changes his spots magnetic storms take 
place on the Earth, when compass needles, telegraph and tele- 
phone apparatus and wireless systems are disturbed. When a 
large number of spots appear at the same time on the Sun the 
Northern Lights are very bright. Sun spots, however, have 
nothing to do with our weather, as the heat reaching the Earth 
is always the same. 

The Sun and the Weather. — Of course the Sun has every- 
thing to do with the weather, but to be able to predict the kind 
of weather we shall have even the next day is a very hard thing 
to do. 



THE SUN, BRIGHTEST OF ALL STARS 35 



The changes in the weather are caused by the heat of the 
Sun alone. The heat of the Sun produces clouds by vaporizing 
the water of rivers, lakes and oceans. He causes hot and cold 
weather by heating some parts of the air more than other parts, 
and this sets the air in motion and we call this movement of the 
air the wind. 

Changes of heat, moisture and wind are the cause of all the 
kinds of weather we have, 
and we have a good many 
kinds, be it hot or cold, 
dry or wet, calm or windy, 
clear or stormy, good, bad 
and indifferent. 

To Forecast the 
Weather by a Barome- 
ter. — The best way to tell 
what the coming weather 
will be in the next few 
hours is by the rise and 
the fall of the pressure of 
the air, or barometric 
pressure, as it is called. 

A simple barometer for 
showing the changes in the pressure of the air can be made of a 
glass tube about 3 feet long, % inch in diameter, and closed at 
one end as shown in Fig. 35. Fill the tube with mercury and, 
placing your finger over the mouth of the tube, turn it upside 
down and put the open end into a cup, or other vessel, which 
is half full of mercury ; in placing it into the cup be careful that 
no air gets into the tube. 

Only a small part of the mercury in the tube will run into 
the cup and this will leave a space in the top of the tube. Now 
fasten a yardstick, the purpose of which is to show the changes 
in the height of the mercury in the tube, with a string or wire to 
the tube, and your barometer will be complete, as shown in 
Fig. 36. 




Fig. 34. — Sun Spot in Photosphere 



36 



THE BOOK OF THE STARS 



Since the air presses on the mercury in the cup but not in 
the tube, the pressure of the air on the mercury in the cup just 
balances the weight of the mercury in the tube and, hence, any 
increase or decrease in the pressure of the air, which ordinarily 
is about 15 pounds to the square inch, is shown by the rising or 
the falling of the mercury in the tube. 

The weather as forecasted by a barometer shows that: (1) 
when the mercury rises in the tube, that is when it is high, the 



OPEN END 




|r-TUBE FILLED 
WITH MERCURY 



I CLOSED END 

Fig. 35. — Barometer Tube. 



CLOSED END 


HIGH -|i 


LOW-^ 

:| 
YARDSTICK : 

CUP : & 
\ # 


OPENEND v y 


Fig. 36. — Barometer Complete 



weather will be fair; (2) when the mercury falls in the tube, 
that is when it is low, bad weather may be looked for; (3) when 
the mercury suddenly falls in the tube a storm is coming, and 
(4) when the mercury continues at a high point the weather 
will remain fair. 

To remember these forecasts easily they may be briefly stated 
thus: 

(1) A high barometer shows fair weather. 

(2) A low barometer shows bad weather. 

(3) A sudden fall of the barometer shows a coming storm. 

(4) A constant high barometer shows continued fair 
weather. 

To Forecast the Weather by Signs. — It will seldom hap- 
pen that a boy who goes camping, or one who otherwise wants 



THE SUN, BRIGHTEST OF ALL STARS 37 

to know what the weather is likely to be on the morrow, will 
have a barometer to consult, so the next best thing is to know 
how to read the weather signs : 

(1) "Red at night is the sailor's delight" is an old forecast, 
and means that the morrow will be a fine day. 

(2) "Red in the morning is the sailor's warning," which 
means that rain is coming. 

(3) A golden sunset is a sign that a high wind is coming. 

(4) A yellow sunset is a sign that rain is coming. 

( 5 ) When the Sun sets clear it is a sign of a fine day on the 
morrow. 

(6) When the Sun sets behind a cloud it is a sign that the 
next day will be cloudy or rainy. 

(7) A misty dawn shows the coming of a fine day. 

(8) A low dawn, that is when the Sun shines clear on 
rising, shows the coming of a fine day. 

(9) A high dawn, that is when the Sun rises over a haze, or 
clouds, shows wind. 

To Light a Fire with the Heat of the Sun. — A small mag- 
nifying glass, or burning glass, is simply a convex lens. It is a 
little piece of apparatus that every boy should always carry 
with him just as he does his pocket knife and compass. A lens 
1% inches in diameter and having a 4-inch focus may be 
bought for 25 or 30 cents. 

A lens of this kind will be found very useful in many ways, 
for it will greatly magnify any object such as cloth, leaves, in- 
sects, finger-prints, in fact anything you may wish to see better 
than you could with your naked eye, though you cannot use a 
single lens for a spyglass. A magnifying glass will also fre- 
quently come in handy for lighting fires, by using the Sun's 
rays when matches are scarce. 

While a Boy Scout would disdain to use paper to kindle a 
fire, yet if a scrap of paper is at hand it will prove a good 
medium on which to direct the rays of the Sun with a burning 
glass. If you have no paper focus your glass on some punk or 
very dry leaves, as shown in Fig. 37. 



THE BOOK OF THE STARS 



To focus the glass means to hold it away from the paper or 
leaves so that the rays of the Sun are brought to a point like 
the sharpened end of a lead pencil; when all the rays of sun- 
^ light, each of 

~3V -/> which carries a 

/'/'lA little heat, are 

* brought to a point, 

they will make 
enough heat to 
light a piece of 
paper or a dry leaf. 
Signaling with 
the Sun's Rays. — 
There are many 
ways of sending a 
signal or a mes- 
sage across space 
by day, as, for in- 
stance, by means 
of smoke, by flags 
and flashes of sun- 
jj\ light; by bonfires, 
Ifty pine-knot flames 
and burning ar- 
rows by night, and 
by wireless, which 
can be used either 
by day or by night. 
A simple and effective way to signal in the daytime when 
the Sun is shining is by using a mirror, that is, a looking-glass, 
as it is commonly called. Every boy knows how to make flashes 
with a mirror, so it will be enough to say here that the glass 
is held in the hand in such a position that the sunlight falling 
upon it will be reflected in the direction you wish to send the 
signals. Fig. 38 shows how it is done. 

Any sort of a code can be used, but it is far more interesting 




Fig. 37. — Boy Focusing Burning Glass on 
Leaves to Maeje Fire. 



THE SUN, BRIGHTEST OF ALL STARS 39 




Fig. 38. — Boy Sending Flash Signal with Mirror. 

and will prove very useful if you are able to send and receive 
messages in the dot and dash alphabet, or Morse telegraph code, 
which is given in Fig. 39. A short flash represents a dot, a 






+#\^:p::±^: 








"rrrttrr^T" 




i ! i i : : : i 



i 



J. 1 



rrrr 



nwpp 



Fig. 39. — Continental Morse Code. 



40 



THE BOOK OF THE STARS 



long flash a dash and short and long flashes represent letters. 
This is the same code that is used for wireless telegraphy. 

How to Make a Simple Heliograph. — A heliograph is 
merely a mirror mounted on a baseboard, but this is a big im- 
provement over holding the mirror in the hand, for to send and 
receive flashes over long distances the mirror must be carefully 
aimed and kept in position. 

To make a heliograph, get a board 12 inches long, 4 inches 
wide and 1 inch thick and cut a piece out of one end 4 inches 



^ftnri 



Fig. 40. — Base for Heliograph. 



long and 1 inch wide, as shown in Fig. 40. Bore a ^-inch 
hole through the slotted end and another 14-inch hole 4% inches 
from the slotted end, as shown in the cut. 

Make a block of wood 4 inches long, 1 inch wide and 1 inch 
thick and bore a 14-inch no ^ e through it near one end. To the 

other end of this 
-BACK Of MIRROR 




HOLE 



stick fasten a mir- 
ror about 4 inches 
square. This mirror 
should be perfectly 
smooth — a plate 
glass mirror is the 
best — and have a 
hole y i6 inch in di- 
ameter drilled 
through the center 
of the mirror for 
sighting the heliograph, as shown in Fig. 41. Any optician will 
drill the hole for you for a quarter or less. Fig. 42 shows a top 
view of the heliograph and Fig. 43 shows a side view of it. 



Fig. 41. — Back View of Heliograph. 



THE SUN, BRIGHTEST OF ALL STARS 41 

Make a wood frame so that the mirror can be fastened in it 
and screw the frame to a stick of wood. Get a bolt 5 inches 
long and % inch in diameter and have a thumb screw fitted 
to it. Set the end of the stick which has the mirror fastened 



I 



? 



Fig. 42. — Top View of Heliograph. 

to it into the slotted end of the baseboard, push the bolt through 
the holes and after slipping on the washer put on the thnmb 
screw. The mirror can now be moved to and fro. 

Into the hole in the front part of the base put a wire or a 



7 



Fig. 43. — Side View op Heliograph. 



thin round stick to sight the mirror by. The heliograph is now 
ready for use. 

After sighting the mirror at the place where the signals 
are to be received, set the mirror so that the reflected beam of 
sunlight shines directly on the place. To send signals in the. 



42 THE BOOK OF THE STARS 

Morse code all you need to do to make dots and dashes is to 
place a sheet of cardboard before the mirror and take it away; 
the length of time the mirror remains uncovered determines 
whether it is a dot or a dash. The heliograph complete is 
shown in Fig. 44. 

How to Make a Simple Sundial.— To make a sundial of 
the usual kind that will give the correct Sun time is not an 




Fig. 44. — Heliograph Complete. 

easy matter, for the spaces marking the hours on the dial are 
not equal as they are on the face of the clock and this will make 
it hard to figure out. 

A kind of sundial that will give the correct Sun time though, 
can be easily made and at little cost. Get a strip of tin 2 
inches wide and 24 inches long; mark it off into 24 equal spaces 
like those on a two-foot rule, and beginning at one end with the 



THE SUN, BRIGHTEST OF ALL STARS 43 

number 1, number each space to 24, as shown in Fig. 45. This 
done, bend the strip of tin into a perfect ring with the numbers 
inside and solder the joint, as shown in Fig. 46. 

Next get a strip of iron or brass % mcn wide, y i6 inch 
thick and 13 inches long; drill a 1 / 16 inch hole through each 



I IT W BT YU WW. K XXI HI 211 XIX XX HI 



MMMIX2K 



zv 



Fig. 45. — Numbered Strip for Sundial. 

end and a %-inch hole 4 inches from one end; bend this strip 
into an exact semi-circle, as shown in Fig. 47 and solder the 
tin ring, at the point where numbers 1 and 24 meet, to the 
middle of the brass semi-circle. Through the holes in the ends 
of the brass semi-circle fasten a wire, and this wire must run 




Fig. 46. — Tin Ring for Sundial. 



exactly through the center of the tin ring. Now screw the 
brass semi-circle to a baseboard (see Fig. 48), so that the 
angle made by the wire and the surface of the board will be 
equal to the latitude of the place where it is to be used ; in other 
words, when the board is level the wire should point directly 
to the North Star and when this is done it will be adjusted to 




Fig. 47. — Brass Semi-Circle with Shadow Wire. 




Fig. 48. — Sundial Complete. 
41 



THE SUN, BRIGHTEST OF THE STARS 45 

the proper angle. The board should be about 12 inches square 
and 1 inch thick. 

Since the shadow of the wire made by the sunlight will fall 
on XII at noon, it will be plain that the shadow of the wire fall- 
ing on the numbers on one side or the other of the ring 
will mark the Sun time. To change Sun time to mean solar 
time, or ordinary time, see Equation of Time, Appendix M.7 L - 

To Find the North by a Watch. — To use a watch as a 
compass, that is to find the north by means of a watch, is easy 




SUN 

■a 



\ NORTH 
^ STAR 

Fig. 49. — To Find the North, by a Watch. 



if the Sun is shining. The watch should be held face up- 
ward ; then turn the watch around until the hour hand points in 
the direction of the Sun. Draw an imaginary line from the 
hour XII through the center of your watch to the hour VI 
(that is the center of the second hand) and produce the line, or 
extend it, as shown by the dotted line. 

If, now, in the middle of these two lines which form an 
angle you draw another line from the center of the watch 
and produce, or extend it, the middle line will point just about 
north, all of which is clearly shown in Fig. 49. 



CHAPTER IV 
THE PLANETS, THE SUN'S KIDDIES 

In the last chapter we said that all the stars in the sky, 
including our Sun, are fixed in their positions ; by this we mean 
that if we were to look at the Big Dipper every night for a 
hundred years we could see no change in the positions of any 
of the stars forming this constellation. 

But if we look at the sky along the line of the ecliptic — that 
is the path of the Sun — one night after another we are likely 
to see a bright point of light which looks exactly like a star 
and yet it is certain that this point of light really does move 
among the other stars. What kind of a heavenly object then is 
this? 

A bright point of light which thus seems to us to be a star 

when we look at it with the naked eye is really another world, or 

planet as it is called, and very like our own Earth. To prove 

. . ^^ that this moving point of light is really a 

^•g f j; world, or planet, and not a distant star, 

all you need to do is to look at it through 

Fig. 50. A Star and a p a [ r £ p era glasses, or a small tele- 

escope. scope, when it will be seen to be a round 

body, whereas a star when viewed through 

the greatest telescope is never larger than a mere point of light. 

(See Fig. 50.) 

The reason the planets, some of which are smaller and 
some larger than our Earth, can be seen to move is because 
they are quite near our Earth ; that is, they are near when com- 
pared with the fixed stars. 

Again, the reason the planets shine like the stars is not 
46 



THE PLANETS, THE SUN'S KIDDIES 47 

because they are hot and flaming bodies like our Sun and the 
other stars, but because the light from the Sun which strikes 
them is reflected to the Earth in exactly the same way that the 
sunlight falling on a mirror is reflected away in another di- 
rection. 

Names and Sizes of the Planets. — The names of all the 
planets, and there are eight chief ones, should be learned as 
well as the order in which they are arranged around the Sun. 
The names of the planets are given below in the order of their 
size. 

Mercury — The smallest planet and the one nearest the Sun. 
Pale ash in color. Has no moon. 

Mars — The Eed Planet. Eeddish in color. Has two moons. 

Venus — Called the Evening Star. Brilliant straw in color. 
Has no moon. 

Earth — Our own planet. Has one moon. 

Uranus (pronounced Yew'-ra-nus) — Called Herschel's 
planet. Pale green in color. Has one moon. 

Neptune — The planet farthest away from the Sun. Has 
four moons. 

Saturn — The planet with the rings. Its color is a dull 
yellow. Has ten moons. 

Jupiter — The largest planet. He is marked with lines 
called belts. He has nine moons. Bright silver in color. 

The Asteroids — A group of small planets, the largest of 
which is about 300 miles in diameter. 

How to Know the Planets. — While it is not an easy thing 
to tell a planet from a star with the naked eye, still there are 
several ways of doing it. 

First, always look for the planets along the path which the 
Sun and Moon travel. As all the planets are in the same plane 
with the Sun and Moon they must all follow the same path 
across the sky. 

Second, it is useful to remember that none of the planets, 
except Mercury, ever twinkle, unless they are very near the 
horizon. 



48 



THE BOOK OF THE STARS 



Third, by watching a planet closely for a few hours it 
will be found to have moved a little. To note this change 
of position the planet and some fixed star near it must 
be closely watched and their distances compared from time to 
time. 

Fourth, and last, the surest way of finding the different 
planets is by using an almanac which will tell you which planets 



A 







Fig. 51. — Sizes of Planets Compared. 



can be seen at certain times of the year and in what part of 
the sky they are to be found. 

Seeing Mercury. — Mercury is so near the Sun that it can 
only be seen with the naked eye at certain times. Mercury 
should be looked for just above the eastern horizon for about 
an hour before the Sun rises in the spring; and above the 
western horizon for about an hour after the Sun sets in the 
autumn. You will have no trouble in knowing Mercury if you 
can only see him, for of all the stars in the heavens he twinkles 
the hardest. His pale ash color will also help you to single 
him out from the stars about him. Mercury goes through 
phases like our Moon, but these cannot be seen with the naked 
eye. 

Mercury is a curious planet in that his day and his year are 
of exactly the same length, just like our Moon; this means that 
he turns on his axis once in exactly the same length of time it 
takes him to travel round the Sun. This causes one side of 
Mercury to be always turned toward the Sun, and of course this 
side is hot and light, while the other side is always turned away 



THE PLANETS, THE SUN'S KIDDIES 



49 



from the Sun and, consequently, it is dark and cold. Three 
views of Mercury as seen through a telescope are shown in 
Fig. 52. 

Mercury is 36 millions of miles from the Sun. 

His diameter is 3,000 miles. 

His day is 88 of our days long. 

His year is 88 of our days long.. 





Fig. 52. — Three Views of Mercury. 



Seeing Mars. — We hear more of Mars than of any other 
planet for two reasons : first, because great lines can be seen on 
his surface which are thought to be canals, and second, since 
Mars sometimes comes closer to the 
Earth than even Venus, there has 
been a great deal of talk since the 
invention of wireless telegraphy about 
our signaling to him. 

That people could live on Mars 
there is no doubt, for the Eed Planet 
is like our Earth, in that it has land, 
water and air, weather and seasons, 
with a warm equator and ice-covered 
poles. Seen through a telescope he 
looks like Fig. 53, though much smaller. 

But Mars cannot always be seen, for sometimes he disap- 
pears for a couple of years, but when he finally does return he 
is a good planet, for he stays a long time, and you cannot mis- 




Fig. 53. — Mars as Seen 
through a telescope. 



50 



THE BOOK OF THE STARS 



take him, for he will shine ruddy and bright with never a merry- 
twinkle. 

Mars is 141 millions of miles from the sun. 

His diameter is 4,200 miles. 

His day is 24% of our hours long. 

His year is 687 of our days long. 

Seeing Venus. — Venus is so much brighter than any of the 
other stars or planets that you will know her the instant you 
see her. Indeed, when Venus is the brightest and the Sun is 






Fig. 54. — Three Views of Venus. 



far enough away from her, she can often be seen with the naked 
eye in the daytime if the sky is clear. Three views of Venus 
are shown in Fig. 54. 

To see Venus you must look for her early in the morning in 
the east before the Sun is up, or in the evening in the west 
just after the Sun has gone down. This is the reason Venus 
is sometimes called an evening star and sometimes a morning 
star. Venus goes through phases like Mercury and our Moon, 
but these cannot be seen with the naked eye. 

When Venus and the Sun get too close together she cannot 
be seen, for the light of the Sun is so powerful that her reflected 
light is dimmed by it. Venus is a bright straw color and she is 
a beautiful object in the sky when visible, but there are months 
at a time when she cannot be seen, either by reason of the Sun's 
rays outshining her or by being hidden from view on the other 
side of the Sun. The day and the year of Venus are, like Mer- 



THE PLANETS, THE SUN'S KIDDIES 51 



cury and our Moon, equal and hence, one side of Venus is always 
turned toward the Sun and basks in its light and heat, while 
the other side is turned away from the Sun and is doomed for- 
ever to cold and darkness. 

Yenus is 67 millions of miles from the Sun. 

Her diameter is 7,700 miles. 

Her day is 225 of our days long. 

Her year is 225 of our days long. 

Our Earth. — The Earth is the third planet in distance from 
our Sun, and although it is small compared with some of the 





Fig. 55. — The Earth. 



Fig. 56. — Jupiter. 



others it is so important to us that it will be described in a 
separate chapter. Fig. 55 shows a view of the Earth as she 
would be seen from the Moon. 

The Earth is 93 millions of miles from the Sun. 

Her diameter is 7,920 miles. 

Her day is 24 hours long. 

Her year is 365 days long. 

Seeing Jupiter. — Jupiter, the largest planet which revolves 
round our Sun, is fifth in distance from him. He is not as 
bright as Venus, but he is brighter than any of the fixed stars, 
and by his brightness and silvery color he is quite easy to recog- 
nize. 

This great planet seems not to have cooled down yet into a 
nice world like our own Earth or someone's else Mars, but 
rather he is a ball surrounded by clouds of hot vapor. Still he 



52 



THE BOOK OF THE STARS 



is not hot enough to give out any light himself, but like the rest 
of the planets he shines by the reflected light of the Sun. Fig. 
56 is a view of Jupiter as seen through a telescope; only one of 
his moons is shown. 

Jupiter is crossed with several bands and he has nine moons 
to light up his great surface on a dark night, but neither his 
belts nor his moons can be seen without a glass. 




Fig. 57. — Saturn. 



Jupiter is 483 millions of miles from the Sun. 

His diameter is 87,000 miles. 

His day is about 10 of our hours long. 

His year is almost 12 of our years long. 

Seeing Saturn. — It is not an easy matter to single out Sat- 
urn with the naked eye, for his light is just about as bright aa 
Capella in the constellation of Auriga, or any of the other first 
magnitude stars. 

This disadvantage is offset by the fact that when he rises at 
sunset he can be seen during the whole night, so that you will 
not only have plenty of time in which to find him, but to observe 
him as well. Again, Saturn may be seen any clear night during 
the winter months until the year 1920. 

Like the Earth, Saturn is believed to have a more or lesg 
solid core, but hotter and with layers of gas around him. It is 
the sixth planet from the Sun, and with his beautiful rings, 
which are formed of millions of little pieces — each a moon in 



THE PLANETS, THE SUN'S KIDDIES 53 

itself — and with his ten large moons, when seen through a tele- 
scope he is far and away the mightiest sight in the whole sky 
at night. He and his wonderful rings are shown in Fig. 57. 

Saturn is 886 millions of miles from the Sun. 

His diameter is 87,000 miles. 

His day is 29 of our days long. 

His year is 29 of our years long. 

Seeing' Uranus. — If you have sharp eyes and will look for 
Uranus in the spring and summer months, you should be able 





Fig. 58. — Uranus. Fig. 59. — Neptune. 

to see him. He has a pale green color, and is a star about as 
bright as the Guardian Stars of the Little Dipper. 

Uranus is the seventh star from the Sun and before Herschel 
discovered him with his homemade telescope astronomers fre- 
quently mistook him for a fixed star. A view of Uranus as seen 
through a large telescope is shown in Fig. 58. 

Uranus is 1,780 millions of miles from the Sun. 

His diameter is 73,000 miles. 

His day is 10 of our hours long. 

His year is 86 of our years long. 

Neptune. — Neptune is so far away from the Sun he cannot 
be seen with the naked eye, and the largest telescope just shows 
him to be a planet. He is attended by one moon. He is simply 
a disk of light when seen through a telescope, as shown in 
Fig. 59. 



54 



THE BOOK OF THE STARS 



Neptune is 2,790 millions of miles from the Sun. 

His diameter is 36,000 miles. 

His day is unknown. 

His year is 165 of our years long. 

The Asteroids. —The Asteroids are a group of small planets 
moving around the Sun in an orbit between the Earth and 
Mars and, hence, at times these little bodies come very close to 




Fig. 60. — Marbles on Top of Table. 



us. The group occupies a place in the sky where we should 
expect to find a single large planet. 

But when the planets were made, Jupiter, with his great 
bulk pulled the soft pieces apart of which a planet would have 
been formed, and instead of one planet of respectable size there « 
are hundreds of little planets ranging anywhere from 20 miles 
to 300 miles in diameter. 

One of these small planets is called Vesta, and although 
she is only 240 miles in diameter she may be seen on certain 
occasions with the naked eye. 

Positions of the Planets Round the Sun. — It was men- 
tioned in the beginning of this chapter that all of the planets 



THE PLANETS, THE SUN'S KIDDIES 



55 



lay in the same plane, and that this plane is in a line with the 
Sun's equator. Now let us see just what this means. 

Suppose we lay eight marbles around a large marble placed 
on top of a table and in the center. This means that all the 



...tBgssHS 215 ** 




^> 






t 



Fig. 61. — Top View op Solar System. 



marbles lie in the same plane which is the top of the table, as 
shown in Fig. 60. The planets are all arranged round the Sun, 
as shown in Fig. 61, just the same as if they were all placed on a 
big, level board or table top. If we draw a picture of the plane 
view of the planets (Fig. 60) and the top view of the planets 



~--e — 



/// 



i / / 



! 1 
I I 
i \ 



\ \ 

\ 



V \ 



^'®r-~ 



/ ///>k\V\ \ 

I I * I I D i 



i \ * \ \ \ K -' / ! I I i 

1 \ \ \ \ v >•' / / / / 

\ \ \ v « \ / / / / 

\ \ \ \ V^X / / / 



\\ 



/ I I 

x ,y / j i 

— / / / 

/ 



\ 



\ 



v 



56 



THE PLANETS, THE SUN'S KIDDIES 57 

(Fig. 61) together, we shall have a picture of the solar system, 
as the Sun and all of his planets are called, as shown in Fig 62. 
From these pictures you will see that the planets have not been 
set around the Sun with any regard to their relative sizes. 

To remember the arrangement of these planets in their rela- 
tion to the Sun commit to memory this simple sentence : 
Men Very Early Made Jars Serve Useful Needs. 
As the first letter of each of the above words is the same as 




Fig. 63. — Egg Shell on Plate. 

the first letter of a planet, you will be able to instantly recall 
the proper place of any one of them. 

How the Planets Are Held in Space. — If you will take an 
ordinary dinner plate and half an eggshell, and give the eggshell 
a slight spin on the rim of the plate — the rim should be slightly 
moistened — you will find that by tilting the plate a trifle the 
eggshell will revolve in two directions; first, it will spin round 
on its own axis, and second, it will travel round the rim of the 
plate, which we will call its orbit, as shown in Fig. 63. 

This double motion of the eggshell is exactly like the double 
motion of a planet — each one turns on his own axis and each 
travels round the Sun in its own orbit ; moreover, all the planets 
travel round the Sun in the same direction, the nearest planets 
taking the shortest time to complete the circle or orbit, while 
those farthest away take the longest time to go round their 
orbits just as we might expect them to do. 

In the beginning of things the planets were a part of the 



58 



THE BOOK OF THE STARS 



Sun, as we shall see further on, and when they were thrown off 
by him they spun round their own axes, and at the same time 
they shot out into space just like a ball spins round its axis as 
it leaves the pitcher's hand. 

The force which causes the ball and the planets to turn 
on their axes while they are shooting off into space is called 
centrifugal force. Now, no one knows what centrifugal force 




""tangent 



Fig. 64. — Boy Throwing Stone to Illustrate Centrifugal Force. 



is, but how it acts is very well known, and you can find out for 
yourself by making the following experiment: 

Take a stone and tie one end of a string to it; now swing 
the stone round in a circle; if the string should break, or you 
should let it go accidentally (on purpose) the stone will shoot 
off at a tangent, that is in a line away from the circle in which 
it was swinging, as shown in Fig. 64. 

This is just what the planets did when they were thrown 
off into space by the Sun, but they could not get very far away, 
for another force which is not only in the Sun but in every 



THE PLANETS, THE SUN'S KIDDIES 



59 



particle of matter in the universe, pulled them back toward the 
Sun, just as it pulls a ball when thrown to the Earth, and this 
force is called gravitation. 

So the centrifugal force keeps them spinning round on their 
axes and flying round in their orbits about the Sun. If it had 
not been for the attractive force of gravitation of the Sun and 
the planets, the planets 
would have kept right on 
going out into space and 
left the Sun to shift for it- 
self forever after. 

As it is they whirl round 
the Sun, never able to get 
any farther from him and 
yet never getting any near- 
er to him, for the centrifu- 
gal force tends to make 
them fly out and away and 
the force of gravitation 
tends to pull them back to 
the Sun. The result is that 
these two great opposing 
forces exactly offset or bal- 
ance each other, and the 
planets are held in their 
orbits just as securely as 
the stone is held out by the 
force the boy exerts to move 
it, and in by the string he holds in his hand. 

This balancing of opposed forces was nicely shown some 
years ago by Sir Robert Ball, the great English astronomer, at 
one of his lectures in the Eoyal Institution of London, and I 
reproduce it here. 

To the ceiling over his lecture table he had fastened a thin 
wire, the lower end of which was secured to a hollow iron ball. 
When the ball was pulled aside, it would swing like a great 




Fig. 65. — Iron Ball Pendulum 
Swinging in Straight Line. 



60 



THE BOOK OF THE STARS 



pendulum, forth and back, in a straight line, as shown in 
Fig. 65. 

But when a powerful magnet was placed on the table and 
the ball was set swinging in a straight line as before, just as it 
came close to the end of the magnet the latter pulled the ball 

with its mighty force 
toward it, and so changed 
its course, but the ball, in- 
stead of being attracted 
directly to it, swung in a 
graceful curve around it, 
as shown in Fig. 66. 

This is precisely the 
case of the planets swing- 
ing round the Sun, and 
shows very nicely the bal- 
anced forces of the Sun 
and the planets and why 
the planets stick to their 
orbits. 

Why the Planets Do 
Not Stop Spinning.— 
Now you may ask why the 
planets do not stop turn- 
ing on their axes and re- 
volving in their orbits 
round the Sun. And the 
answer is because there is nothing to stop them. 

If you spin a top on a plate it may keep going for a long 
time, but it will finally die down and stop. This is because 
there are other forces which oppose its centrifugal force. The 
forces a spinning top has to overcome are friction between the 
point of its spindle and the plate, and the resistance between 
the surface of the spinning top and the air pressing on its sides, 
and the friction and the air resistance together soon use up 
the energy stored in the top and which makes it spin. 




Fig. 66. — Iron Ball Pendulum 
Swinging in Curved Line. 



THE PLANETS, THE SUN'S KIDDIES 61 

But if you could spin and throw a top far enough away from 
the Earth so that it would not meet with friction or resistance 
of any kind, it would go on spinning forever just like the 
planets. 

How to Plot the Position of a Planet. — One of the tests 
which a Boy Scout must pass in order to obtain a merit badge 
for starcraft is to "plot on at least two nights per month for 
six months the positions of all naked-eye planets between sun- 
down and one hour thereafter. The plot of each planet shall 
contain at least three fixed stars with their names and desig- 
nations, colors of planets and stars to be recorded by him." 

Now, by looking at your almanac under the head of Morn- 
ing and Evening Stars you will find all the planets which are 
listed as Evening Stars, together with the dates when they can 
best be seen. From your almanac for 1915 you will learn that 

Mercury is an evening star, and can be seen about Feb. 5, 
May 31 and September 27 in the west, just after, sunset; that 

Venus will be an evening star from September 12 for the 
rest of the year; that 

Jupiter will be an evening star until February 24; after 
that a morning star until September 17, and then an evening 
star for the rest of the year, and that 

Saturn will be an evening star until June 28. 

The first thing to do is to find what constellation is on your 
meridian at 9 P. M. for the month that the planet you wish to 
plot is to be seen. This you can do by looking at the map of the 
stars shown in Fig. 67. You can see any of the stars or con- 
stellations on your meridian by looking for them at 9 o'clock 
P. M. on the months marked above them. 

This done, consult your almanac and find out what time 
the Sun sets on the day that the planet you are looking for can 
be seen. 

As an example let's take Mercury, which the almanac says 
is an evening star about February 5, and which can be seen in 
the west just after sunset. The almanac will also tell you that 
the Sun sets on February 5 at 5 o'clock. 



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THE PLANETS, THE SUN'S KIDDIES 



63 



The star map (Fig. 67) will show you that the constella- 
tion of Gemini, the Twins, is one which can be seen in February 
on your meridian at 9 o'clock at night, and you know that Mer- 
cury can be seen close to the western horizon from 3 to 4 hours 
earlier. 

Since Gemini, the Twins, is on the meridian at 9 o'clock, 
Taurus, the Bull, which is the next constellation to it, will be 
on the meridian at 7 o'clock, and Aries, the Earn, will be on the 
meridian at 5 o'clock. 

Now the next constellation to the west of Aries, the Earn, is 
Pisces, the Fishes, and the next one to Pisces, the Fishes, is 




CAST 



WEST 



Fig. 68. — Diagram of Position of Constellations. 



Aquarius, the Water Bearer, and as this constellation sets about 
an hour after the Sun, it is in this constellation that you will 
find Mercury in the early February evenings. 

The diagram (Fig. 68) shows how it is that when Aries is 
on the meridian at 5 o'clock in the evenings of February, Gemini 
will be rising in the east, and Aquarius, with Mercury in it, 
wilKbe getting ready to set in the west. 

You can find all the other planets in the same way, but it is 
much easier to find them in the sky than it is to try and im- 
agine their positions after reading how it is done. You should, 
though, by all means, read the chapter on The Stars of the 



64 



THE BOOK OF THE STARS 



Zodiac before you try to plot a planet, for there is much useful 
information in it which you ought to know. 

To plot the position of a planet, take a sheet of stiff paper 
or cardboard about 8 inches square and divide it into a square 



GAMfflA 

10 DEGREES 

NORT 



10 DEGREES 

SOUTH 




NO OF CHAPT-3 DATE- FEB 5 TIMES-6PW. 

NAAfE OF PLANET- F7F/ZCU/ZY A64STE OF N&QPE5T 5T4R.S 
COLOP OF PLANET- PALE A5N ALPHA <5 BETA 7/V ' PEGA5U5 
NAME . W/LL/ANf BZOWN FOPF1ALHAUT /N50UT/iEPNF/Jff 
COLO/Z OF sr/?/zs 

<4LPNA C BETA, W/-//TE FOPAtALAAUT, 3T&4U/ 
Fig. 69. — Plotting Position of Planet. 



6 inches on the side, as shown in Fig. 69. This will leave a 
margin of 1 inch on both sides, % inch on top and 1*4 inches 
at the bottom of your paper. 

Fasten the paper to your starboard, described in Chapter 
II, and go forth with it and your acetylene or flash lamp and 
find your planet. Having found it, mark with a pencil in the 



THE PLANETS, THE SUN'S KIDDIES 65 

squares on your ruled paper the positions of three of the nearest 
fixed stars which are shown in the star chart of Fig. 67. Now 
mark the position of the planet as you see it on your chart by 
making a little circle and your outdoor observation is ended. 

Once inside mark down the chart number, the date and the 
time you made the observation ; also the names and colors of the 
stars and the planet, and finish the record by signing your name. 
Should any of the other planets be visible at the time of your 
observation you will, of course, have to plot two charts, unless 
the planets are very near each other. 



CHAPTER V 
MOTHER EARTH, OLD ADAM'S PLANET 

The Earth in the Making. — The Earth on which we live 
and find so much that is interesting was once a part of our 
Sun just as the other planets were. 

When the Sun was being made of star stuff great quantities 
of gases were set into mighty whirls, and when these acquired 
enough force they shot off into space like so many cannon balls, 
and they are still a-whirling. 

But these new-born planets could only get a certain distance 
away from the Sun, as we have learned, for the force of his 
attraction offset the force of their motion with the result that 
they are still held in space around him. 

One of these whirling bodies was the Earth, and when it 
had comfortably settled in its orbit and slowed down a bit it 
began to cool off and a crust was formed on its liquid surface, 
just as ice is formed when water is frozen. Then some of the 
gases condensed into water and others became air and when the 
Earth had cooled down still further some millions of years af- 
terward it became a more or less suitable place for human be- 
ings to live on. 

While the Earth has cooled off until it is possible for us to 
live comfortably on its crust, it is still warm outside and very 
hot inside. This is proved by volcanoes which throw out white- 
hot lava and gases when they are in eruption. 

If it had not been for the light and heat of the Sun in the 
past ages there never could have been any kind of life on the 
Earth. The Earth is just as dependent on the Sun now as it 
was in the past, and if he should fail to shine on our world for 

66 



MOTHER EARTH, OLD ADAM'S PLANET 67 

even a little time everything would die. Fig. 70 is a cross 
section of the Earth. 

To Prove the Earth is Round. — Every boy knows that the 
Earth is round, but the wisest of men did not know it for cer- 
tain until about 400 years ago, when one of Magellan's ships 



NORTH POLE 




RUST 

ATMOSPHERE 



SOUTH POLE 
Fig. 70. — Cross Section of the Earth. 



made a complete voyage round the world and returned to the 
place she started from. 

(1) One of the easy ways to show that the earth is round, 
or at least that the surface of the earth is curved, as shown in 
Pig. 71, is to watch a ship as she sails out to sea. All of the 




Fig. 71. — Sails op Ship Can Be Seen After Hull Has Disappeared. 



ship—hull, sails and smokestack, if she has one — can be seen 
until she sails over the horizon, and then her hull, which is the 
largest part of her, is lost to view, then her sails and stack, and 
finally only the tops of her masts can be seen. It is a pretty 
good sign that the Earth is a ball. 

(2) A very pleasant way to prove the Earth is a ball is to 



68 



THE BOOK OF THE STARS 



^q\JAT 0/? 




take passage on a ship that makes a round-the-world cruise. 
If you leave New York and keep sailing east all the time you 
will finally land at San Francisco; keep on going east by rail 
and you will find yourself back in dear old New York, where 
you started from, having gained a day on the way. See Fig. 72. 
To Prove the Earth Turns on Its Axis. — (1) Having 
proved that the Earth is round, the next thing to do is to prove 
that it turns about on its axis. 

(1) The best known experiment for showing that the Earth 
really turns on its axis was made by Foucault (pronounced 
Foo-ko'), a French philosopher, in 1851, 
who used a pendulum for the purpose. 

In the top of a great dome in a build- 
ing in Paris, called the Pantheon, Foucault 
hung a large metal ball by means of a wire 
about 150 feet long. On the floor he made 
a mark, exactly under the ball, running due 
north and south. Then drawing back the 
ball, he let it go, when it swung directly 
over the line. 

The heavy pendulum, which after being started swung for 
hours, seemed to move away from the line toward the west, but, 
instead, it was the Earth which was really turning round under 
the swinging pendulum. Fig 73 shows how the line on the floor 
moved with the Earth from under the ball. You can repeat 
the experiment if you can get a heavy ball and a place high 
enough to fasten a wire 30 or more feet in length. 

(2) A much simpler way to show the turning of the Earth 
on its axis, though this experiment does not show the Earth's 
motion as clearly as the pendulum, is to make a photograph of 
the North Star and the stars in its neighborhood, as explained 
in Chapter XII. 

During the time the sensitive plate is being exposed the 
camera will be carried round by the Earth turning on its axis 
and the fixed stars will leave bright trails on the plate in arcs 
of circles. 



Fig. 72. — Sailing 
Round the Earth. 



MOTHER EARTH, OLD ADAM'S PLANET 69 

The Earth Turning on Its Axis Makes Day and Night. 

— The Earth, in turning round on its axis once every 24 hours, 
receives the light of the Sun on half of its surface at a time, 
making the day, while the other half is in the shadow, which 
makes the night. 

If the equator of the earth was in a plane with the Sun, 
as shown in Fig. 74, it is easy to see that the days and nights 



15 DEGREES, 1 
*l HOUR 



o 






15- 



PENDULUM 
ALWAYS SWINGS 

\ ON A STRAIGHT 

\LINE 



m 1 rn 



1 BALL STARTS 
HERE 



Fig. 73. — The Earth Moves Away from the Swinging Pendulum. 



all over the world would be of the same length, that is, each 
would be 12 hours long. Instead, the Earth tilts a little, as 
shown in Fig. 75 — to be exact, its axis tilts 231/2 degrees out of 
the perpendicular and this makes the day and the night at the 
equator each 12 hours long and the day and the night at the 
north and south poles each six months long. 

The line round the Earth which is in a plane with the Sun 
is called the ecliptic, and for this reason the Sun seems to follow 



70 



THE BOOK OF THE STARS 



a path round the Earth that is in a line with the ecliptic, and 
this is called the path of the Sun. 

To Show That the Earth Travels Round the Sun.— When 
we look at the Sun and the stars it is hard to believe that they 



NORTH POLE 




SOUTH POLE 

Fig. 74. — If the Earth's Equator Was in a Line with the Sun. 



are standing still and that it is the Earth which is whirling 
round on its own axis and also round the Sun. 

We have given a couple of experiments to show that the 





[SfJHJ 



Fig. 75. — The Earth Tilts on Its Axis. 



MOTHER EARTH, OLD ADAM'S PLANET 71 

Earth turns on its own axis, and here is one to show how the 
Earth travels in a great circle, or rather ellipse,, round the Sun 
and gives us our year. 

It does more, for the Earth being tilted off the perpendicu- 
lar, its movement round the Sun causes the north pole to he 
turned toward the Sun half of the time, and then the south pole 
to be turned toward the Sun an equal length of time, which 



^::...^f..--i.-c.-.-. 


j:==-9 




Fig. 76. — Light in Room to Represent Sun. 



gives each of them a day and a night that is six months long. 
In the center of a large room set a light so that it will be 
about as high as your eyes. Let this light represent the Sun; 
you must play now that you are the Earth, and think of the 
pictures on the wall as being the stars fixed in the sky away 
off in space. Now walk in a circle around the light toward 
the right and facing the light all the time. As you move 
around the light you will see that it seems to move with you in 
a circle and also that it seems to move past the pictures on the 
wall. The experiment is shown in Fig. 76. 



72 THE BOOK OF THE STARS 

This, then, is exactly what happens when we look at the Sun 
and the stars. The Earth moves round the Sun in a circle, 
nearly, and since the Sun is so much closer to us than any of the 
other fixed stars the Sun apparently moves by the stars, be- 
cause the Earth changes its position relative to it and the stars. 

The Earth Turning Round the Sun Makes the Seasons. 
— We have seen how the days and nights would be equal all over 
the world if the equator of the Earth was in a plane with the 
Sun, but since the Earth is tilted the days and nights are 
unequal except twice a year, and this is when the places where 

the ecliptic and the equator 

cross each other are facing 

BLUNT END PENCIL^^p^V Kx. a 

the Sun. 

axisofto^ ^l^-^j Again, if the Earth's 




equator was always in a plane 
with the Sun the light and 
heat would be about the same 
Fig. 77.— Top Spring on Plate. all over the world and there 

would be no seasons. But 
the Earth having its axis tilted, and which is always set in the 
same direction, together with the Earth speeding in a circle 
around the Sun, causes some curious things to happen and the 
seasons are one of them. 

To make clearer the reason the axis of the Earth always 
stays in one position take a top and give it a good spin. The 
top, of course, turns round its axis very fast, and this is like 
the Earth turning round its axis every 24 hours. 

Xow, if you place the blunt end of a pencil on the upper 
axis of the spinning top, as shown in Fig. 77, and try to tilt it 
in some other direction than that it took when it began to spin, 
you will find it rather a hard thing to do. In other words, once a 
body is rapidly turning on its own axis it very strongly tends 
to keep its axis pointing in the same direction. 

This rule also applies to the Earth, for having been tilted 
at an angle when it was thrown off by the Sun in the making, 
no other forces have ever been able to change the position of 



MOTHER EARTH, OLD ADAM'S PLANET 73 

its axis to any great extent, though the Earth spins easily on 
its axis and also revolves round the Sun. 

To understand how the seasons are made you must first 
have clearly in mind the positions of the tilted Earth in differ- 
ent parts of its orbit round the Sun. The things needed for 
this experiment are a nice round apple, a candle, a piece of 
string, a safety pin and a knitting needle. 




Fig. 78. — Circle Around Candle Marked with Seasons. 



Place the candle in the center of a table and call it the Sun ; 
draw a circle a foot in diameter on the table top and around the 
candle with a bit of chalk. Mark one side September 22; at 
the next quarter of the circle mark December 21; directly oppo- 
site the September mark chalk in March 21, and finally between 
March and September mark June 21, all of which is shown in 
Fig. 78. 

Push the knitting needle through the center of the apple, 
call the apple the Earth and call one end of the knitting needle 



74 



THE BOOK OF THE STARS 



the north pole and the other end the south pole. Fasten the 
safety-pin through the skin of the apple and tie the string to 




KNITTING 

NEEDLE 



Fig. 79. — Apple to Repre- 
sent Earth Suspended 
in Air. 




Fig. 80. — Position op the 
Earth and Sun in Autumn. 



the pin so that when the string is tied to a tack in the ceiling 
or some one is holding it directly over the candle the knitting 




Fig. 81. — Position 
of the Earth and 
Sun in Winter. 




Fig. 82. — Position op 
the Earth and Sun 
in Spring. 



needle of the apple will be tilted to the perpendicular, as shown 
in Fig. 79. 

Now grasp the top of the needle, which is the north pole, 



MOTHER EARTH, OLD ADAM'S PLANET 75 



with tiie left hand and hold the apple away from the candle, as 
shown in Fig. 80. This is the position of the earth to the Sun 
on September 22, when the Sun passes di- 
rectly over the Earth's equator, and for us 
autumn is at hand. 

Now pull the apple by its north pole 
toward you and around one quarter of the 
circle chalked on the table, as shown in 
Fig. 81, which is the position of the Earth 
to the Sun on December 21. You will see 
that the north pole is away from the light 
and heat and hence it is dark and winter 
there; but the south pole on the other end 
is getting plenty of light and heat and it 
is both day and summer there. This marks 
the beginning of our winter. 

Push the apple by its north pole — always being careful to 
keep the knitting needle tilted in the same position — around 




Fig. 83. — Position 
of the Earth and 
Sun in Summer. 



AUTUMN EQUINOX 
, SEPT. 22 



^ 






WINTER (X^ 

solsticeV 

OEC2I 



V 




VERNAL EQUINOX, 
MARCH 21 

Fig. 84. — Cycle of Seasons. 



another quarter of a circle and this is where the Earth is in 
its orbit, and its position to the Sun on about March 21. Once 



76 



THE BOOK OF THE STARS 



again the Sun is over the Earth's equator and all parts of our 
world are then lighted and heated equally, and we have the be- 
ginning of spring. See Fig. 82. 

Again push the apple around another quarter circle and 
June 21 is reached. This time you will find the north pole is 
turned toward the Sun and this 
time it gets the light and heat for 
six months, while the south pole 
is away from the Sun and takes 
its turn of six months of night 
and winter. To us, however, it is 
the beginning of summer. Fig. 
83 shows the position of the 
Earth to the Sun at this time. 

Pull the apple one more quar- 
ter of the circle round the candle 
and you will have completed its 
orbit just as the Earth swings 
round the Sun in 365 days. The 
seasons are more clearly shown in 
Fig. 84. 

The North Pole. — The north 
pole is not only one of the ends 
of the axis round which the Earth 
turns but close to it is the north 
magnetic pole as well. By mag- 
netic we mean that the Earth be- 
haves like a steel bar that has been 
magnetized. 
A steel bar magnet like that shown in Fig. 85 is strongest 
at its ends. One end is positively magnetized, and we call this 
end its north pole, and the other end is negatively magnetized, 
and we call this end its south pole. 

Magnetic lines of force stream from the south pole through 
the steel bar and reaching the north pole they stream through 
the air to the south pole, as shown by the curved lines, thus 




Fig. 85. — Lines of Force 
through and around a 
Magnet. 



MOTHER EARTH, OLD ADAM'S PLANET 77 



n.M'/O-, 







forming a magnetic circuit, 

just as two wires joined to- 
gether may form an electric 

circuit. 

If we place a compass 

needle near the steel bar 

magnet the needle will turn 

in the same direction as the 

magnetic lines of force are 

flowing, and it will, there- 
fore, point to the north and 

to the south poles of the 

magnet. 

Now the Earth is a 

great magnet with a posi- Fig. 86.— Lines of Force around 

tive pole, which we call the T3E Earth. 

north pole at one end of its 

axis, and a negative pole, which we call the south pole, at 

the other end of its axis, as shown in Fig. 86. 

Like a bar magnet, magnetic lines 
of force stream all over the Earth's 
surface from the north pole to the 
south pole, and a compass needle 

placed anywhere on the Earth will swing round until it is in 

the same direction as the lines of magnetic force. 

How to Make a Simple Com- 
pass. — Take a piece of watch 

spring about 3 inches long and 

straighten it. Heat the middle 

red-hot and let it cool slowly, 

when the temper will be taken out 

of it at this point. Place a center 

punch in the middle of the spring 

and strike it a sharp blow with a 

hammer; this will make a little dent in it. Bend it as shown 

in Fig. 87. To magnetize the needle rub one end on the north 



Fig. 87. — Watch Spring — 
Needle for Compass. 



^WATCH SPRING 



STEEL SEWING 
NEEDLE 




CORK 



Fig. 



Com- 



78 



THE BOOK OF THE STARS 




, — Pocket Watch-case Compass. 



pole and the other end on the south pole of a steel magnet. 

Stick a sewing needle into a large cork and lay the magnetized 

needle on it, when it will point north and south, as shown in 

Fig. 88. 

Boxing the Compass. — There are two kinds of compasses 

in general use, though 
both kinds use a mag- 
netized needle. The 
first kind is the ordi- 
nary pocket compass, 
with either a pull-off 
cover or one of the 
watch-case pattern. In 
this kind of a compass 
the magnetic needle is 

fitted with a jeweled center which swings on a steel needle; 

the dial is fixed in the case and is marked with the cardinal 

points, that is with the chief points of a compass. Fig. 89 

shows a pocket watch-case compass. 

In the mariner's com- 
pass, which is used at sea, 

the compass card and the 

magnetic needle are fast- 
ened together. The card 

is made of a circular sheet 

of mica and the points of 

the compass, which are 

called rhumbs, are marked 

on the edge. The needle 

and card float in a bowl of 

mercury. 

The card is marked 

with 32 rays, forming a 

many-pointed star, and 

each of these points has 

cardinal points being north, east, south and west. 




Fig. 90.- 



5 i " 
-Dial of Mariner's Compass. 



a name, the names of 



the four 
To know 



MOTHER EARTH, OLD ADAM'S PLANET 79 

all of the points by heart and be able to name them, beginning 
with the north and going round the card to the north again, is 
what sailors call boxing the compass. See Fig. 90. 

Points on Compass Card Names of Points 

N North 

N bE North by east 

NNE North, northeast 

NE bN Northeast by north 

NE Northeast 

NE bE Northeast by east 

ENE East, northeast 

E bN East by north 

E East 

E bS East by south 

ESE East, southeast , 

SE bE Southeast by east 

SE Southeast 

SE bS Southeast by south 

SSE South, southeast 

N bE South by east 

S South 

S bW South by west 

SSW South, southwest 

SW bS Southwest by south! 

SW Southwest 

SW bW Southwest by west 

WSW West, southwest 

W bS West by south 

W West 

W bN West by north 

WNW West, northwest 

NW bW Northwest by west 

NW Northwest 

NW bN Northwest by north 

NNW North, northwest 

N bW North by west 

N North 

Dial of a Mariner's Compass 

How to Make a Simple Dipping Needle. — When a com- 
pass needle is pivoted so that it can swing up and down, that is, 
to and away from the earth, it is called a dipping needle. 

Such a needle will dip toward the nearest pole of the earth. 



80 



THE BOOK OF THE STARS 



At the equator there is no dip, that is, the needle will stand 
parallel with the Earth's surface. 

At the north pole the needle will stand straight up and down 
in a line with the axis of the Earth. The dip, therefore, of the 



KNITTING NEEDLE 



\ 



SEWING NEEDLE 



Fig. 91. — Needle for Dipping Needle. 

needle at any place on the Earth's surface is just about that of 
the latitude of the place where it is used. Dipping needles are 
also used by miners for finding iron ores. 

To make a dipping needle, slip a small cork over a knitting 




Fig. 92. — Dipping Needle Complete. 



needle and push a sewing needle through the cork at right angles 
to the knitting needle, as shown in Fig. 91. Now lay the sew- 
ing needle with its ends on the edges of two tumblers, and see 
that the knitting needle is perfectly balanced. This done, mag- 




O EQUATOR 



Fig. 93. — Protractor Showing Degrees. 



NORTH POLE 
80 3° 




o DEGREES 



90 
SOUTH POLE 

Fig. 94. — Earth Surface Divided into Degrees. 



81 



82 



THE BOOK OF THE STARS 



netize the knitting needle by rubbing one end on the north pole 
of a steel magnet and the other end on the south pole of the 
magnet. Make a little wood stand as shown in Fig. 92 and 
place the ends of the sewing needle on the wood supports. 

The latitude running through the middle of the United 
States is about 40 degrees north of the equator and if you live 




Fig. 95. — Protractor Set by Dipping Needle Showing Latitude. 



in this latitude the dip of your needle will be about 40 degrees 
from the horizontal. 

How to Find Latitude. — The latitude of a place on the 
Earth's surface is its distance north or south of the equator. 
This distance is usually measured in degrees of a circle, instead 
of in miles. 

The equator is called (zero) degrees, and the north and 
south poles are 90 degrees from the equator, as shown in Fig. 93. 
If you are in Philadelphia, Pennsylvania, or Quincy, Illinois, or 
Tehama, California, you are in latitude 40 degrees. If you are 
in Bangor, Maine, St. Paul, Minnesota, or Portland, Oregon, 
you are in latitude 45 degrees, or just halfway between the north 
pole and the equator, as Fig. 94 shows. 



MOTHER EARTH, OLD ADAM'S PLANET 83 




Fig. 96. — Two Sticks Screwed 
Together. 



NORTH STAR,* 



(1) An easy way to find roughly the latitude of a place, 
that is, its distance from the equator, is to use a dipping needle 
and a protractor. 

To make a protractor cut out 
a semi-circle of stiff, white card- 
board, just the size shown in Fig. 
93, and mark the figures on 
the edge and draw lines from 
the edge to the center point 
exactly as in the picture. 

Now place your dipping 
needle on a level board or table and set your cardboard pro- 
tractor by the side of it, as shown in Fig. 95. Whatever line 
on the protractor the dip of the needle takes the degree marked 
on the edge of the protractor will be about the latitude you 
are in. 

(2) Another way to ob- 
tain latitude is to take two 
smooth pieces of wood, 
about 1 foot long and 14 
inch thick, and hinge them 
together at one end with a 
screw, as in Fig. 96. Now 
set a bucket out-of-doors in 
an open space from which 
the North Star may be seen, 
fill the bucket with water 
and level it up until the 
water is parallel with the 
rim all the way round. 

When night falls find 

the North Star and set your 

sticks across the rim, as shown in Fig. 97. Eaise one of the 

sticks and sight it until it points straight at the North Star, 

and having done this you are through with the observation. 

Take the sticks into the house, being very careful not to 




Fig. 97. — Two Sticks Across Bucket 
of Water. 



84 THE BOOK OF THE STARS 

change their relative positions, so that the angle they form can 
be measured with a protractor. Tack a piece of paper on your 
starboard and draw a straight horizontal line on it. 

Lay the stick that was on the bucket on the horizontal line, 
and draw a line along the edge of the other stick with which 
you sighted the North Star, as in Fig. 98. 

Now measure the distance, in degrees, between the two lines 
with your protractor and the number of degrees you get will 
be roughly the latitude. 

Shooting the Sun. — Another and very exact way to find 
the latitude, and which is also used to help find longitude when 



HORIZONTAL LINE 

Fig. 98. — Protractor and Sticks on Drawing Paper. 

at sea, is by means of an instrument known as a sextant, so 
called from the fact that it is formed of a sixth part of a circle. 

It is made with a metal frame A and having the degrees 
marked on its curved edge B like a protractor. On one end of 
a thin strip of metal, or arm, C (see Fig. 99), a mirror, D, 
called an index mirror, is rigidly fastened, and right under the 
center of this mirror the arm C is hinged to the frame A. The 
other end of this arm slides over the scale B. 

To the left side of the frame also rigidly fastened is a second 
glass E called a horizon glass, and half of which is clear and 
half silvered. A telescope is also rigidly fastened to the frame 
A directly opposite but in a line with the horizon glass E. 



MOTHER EARTH, OLD ADAM'S PLANET 85 

Now to find the latitude by taking the Sun, or as sailors 
sometimes call it, shooting the Sun, in order to learn the posi- 
tion of the ship at sea, the sextant is held in both hands firmly, 
and the horizon which is sighted through the telescope is brought 
into view through the clear part of the horizon glass E. 

The arm C, carrying the index mirror D, is now moved over 
the scale A until the light from the Sun just as it crosses the 
meridian at noon is reflected by its polished surface into the 
silvered part of the horizon glass E, and this reflects the sun- 
light into the telescope right in a line with the line of sight to 




Fig. 99. — Sextant in Use. Shooting the Sun. 



the horizon. This forms an angle of the two beams of light 
just as an angle is formed of the two sticks of wood in the pail 
experiment and the number of degrees the end of the arm C 
points to on the scale B is the latitude in degrees or the distance 
of the ship north or south of the equator. 

Haw Longitude is Found. — To find the longitude at sea, 
that is, the position of a ship east or west of a given place, is 
just as simple a matter as finding the latitude or its posi- 
tion north or south of the equator. Two instruments are used 
to find longitude, and these are the sextant, which has just 
been described, and a very accurate clock, called a chronometer 
(pronounced chro-nom'-e-ter) . 



86 THE BOOK OF THE STARS 

As you know, imaginary lines running from the north pole 
to the south pole are called meridians of longitude. Now the 
Earth has been divided into 24 of these lines, the zero meridian, 
from which distances east and west are measured, running 
through Greenwich, England. 

There are 24 of these standard meridians and hence they are 
15 degrees apart — since there are 360 degrees in a circle — and 
they are 1 hour apart — since there are 24 hours in a day, and 
therefore 15 degrees equal 1 hour. (See Chapter X, The Time 
o* Day.) 

Now, since it is 12 o'clock noon when the Sun passes 
over any one of these standard meridians, it will be 11 
o'clock A. M., 15 degrees west of it, and 1 o'clock P. M., 15 
degrees east of it, and consequently there will be an hour's 
difference in the time, either fast or slow, for every 15 degrees, 
depending on whether you count east or west from the noon 
meridian. 

The purpose of a sextant in finding longitude on shipboard 
is to know when it is exactly noon by the Sun, and in this way 
the local time is found. The purpose of a chronometer is to 
carry exact Greenwich time, and the difference between the 
local time found each day by taking the Sun, and Greenwich 
time shown by the chronometer gives the distance in degrees the 
ship has traveled from Greenwich. 

By knowing the latitude and longitude of a ship the distance 
in miles north and south and east and west from any port can 
be figured out without much trouble. 

The reason that a very accurate clock has to be carried is 
that a difference of a few seconds either too fast or too slow 
will affect the calculations just that much, and this means that 
the ship will be thrown out of its calculated position by several 
miles. 

To correct the observations with the sextant and the in- 
accuracy of the chronometer, etc., are a part of the business of 
the navigating officer, and he is provided with tables and things 
to make this work as easy and certain as is possible. 



MOTHER EARTH, OLD ADAM'S PLANET 87 

How to Know When Yon Are at the North Pole. — If you 

should ever reach the north pole where overhead is north and 
every other direction is south how would you know it? 

Suppose you were standing on the exact top of the world 
during one of its long polar nights, then the North Star would 
be directly over your head and the Big Dipper and Cassiopeia 
would serve to mark the passing of days as well as of nights, 
that is, if you were at the north pole in the wintertime. 




9 



„*— — -*^3PM 



"■"HP-** «'«l.4.*Mttaft«<* 

Fig. 100. — Shadows at the North Pole. 



But if you were there during a long Arctic day, that is, in 
the good old summertime, you could see the Sun making a 
great circle, or seem to, once in 24 hours, always keeping the 
same position, and never going higher or getting lower. 

Explorers use a sextant to find out when they are at the north 
pole, and they sight the Sun's height above the horizon at morn- 
ing, noon and night. If the angle the Sun makes with the hori- 
zon is the same every time he is observed, the explorer knows he 
is standing on the very point round which the Earth turns. 
Then he plants a stick in the snow and ice on the north pole, 



88 THE BOOK OF THE STARS 

hoists the American flag, and hurries home as fast as dogs and 
ships and trains can carry him to tell about it. 

If you ever reach the north pole you can know it, too, even 
though you haven't a sextant with you. All you need to do, 
when you think you are standing on the north pole, is to notice 
the length of your shadow five or six times in 24 hours. If the 
length of your shadow is exactly the same every time you look 
at it, as shown in Fig. 100, you are really and truly at the 
north pole. 

Difference Between the True North Pole and the Mag- 
netic North Pole. — The compass and dipping needle do not 
point to the true north pole, for the magnetic north pole and 
the true north pole are not located at the same place. 

The magnetic north pole was found by Captain Eoss in 
1832. At that time the magnetic north pole was northwest of 
Hudson's Bay in about latitude 70 degrees north and longitude 
96 degrees and 45 minutes west, that is, west of the zero 
meridian which runs through Greenwich. 



CHAPTEE VI 

THE MOON, THE EARTH'S DAUGHTER 

How the Moon Was Made. — There was a time away back 
in the beginning of the planets when the Earth did not have a 
Moon. 

Two ideas have been worked ont to acconnt for the birth of 
the Moon and these are somewhat alike, for both agree that 
just as the Earth was once a part of the Sun and was whirled 




MOON 



EARTH 

Fig. 101. — Moon and Earth Joined Together Like a Dumbbell. 

off into space and became a planet so the Moon was once 
a part of the Earth and was thrown off and became her 
daughter. 

The first idea as to how the Moon was made is that a smaller 
core was formed in the gaseous matter of the Earth and that 
this core and the core of the Earth, which were at first joined 



90 



THE BOOK OF THE STARS 




Fig. 102. — Balls Con- 
nected with an Elastic. 



together like a dumbbell, as shown in Fig. 101, began to spread 

apart like a pair of balls fastened together with a piece of elastic 
when they are whirled rapidly 
round each other, as shown in Fig. 
102. 

So, too, the high speed with 
which the Earth turned on its axis 
when it was in the making caused 
the smaller part to fly off its handle 
and it became the Moon. 

The second idea is like the first, 
except that the Earth is thought 
to have cooled down until it was a 
melted mass, and it was then that 
a great upheaval took place in 

which a part, one-eightieth as large as that of the world itself, 

was torn out of its side and, whirling away by centrifugal 

force, the Moon was born. 
To throw off such a 

mighty part of its bulk 

as the Moon, it has been 

figured out that the 

Earth must have made a 

complete turn on its axis 

every 2 hours, instead of 

one turn in 24 hours, as 

it now does; and it was 

while the Earth was 

turning at this terrific 

rate of speed that the 

centrifugal force over- 
came the force of gravi- 
tation and tore the 

Moon from the Earth's side and formed a little world of its own. 
It is believed by some astronomers that the Moon was once 

that part of the Earth which is now filled up by the waters 




Fig. 103.— Map Showing Pacific Ocean. 



THE MOON, THE EARTH'S DAUGHTER 91 

of the Pacific Ocean and there are several reasons why this 
seems very likely. 

First, if the waters which form the Pacific Ocean were rolled 
into a big ball it would be just about the size of the Moon; 
second, the space between the coasts of North and South Amer- 
ica on the east, and Asia and Australia on the west, will be seen 
by referring to Fig. 103 to be roughly circular in form; third, 
there is a marked likeness between the volcanoes in California, 
in the Hawaiian Islands and in Japan to those on the Moon; 







'^i&m'-imz 









Fig. 104. — Imitating the Volcanoes in the Moon. 

and fourth, the Hawaiian Islands seem to have been the axis or 
hub round which the melted mass forming the Moon began to 
spin until it became a ball, when the combined action of the 
Earth's centrifugal force and the Sun's attraction caused it to 
fly away. 

It was, doubtless, at this long ago time that the great vol- 
canoes of the Moon, as well as those of the coasts of and on 
the islands in the Pacific Ocean were made, but what caused 
them can only be guessed at. There are two ideas, also, to 
account for them; one is that the pent-up gases inside the 
Earth and the Moon exploded and so threw up the volcanoes; 
the other idea is that showers of gigantic melted masses fell on 
the surface of both the Earth and Moon and so caused them. 



92 



THE BOOK OF THE STARS 



An experiment to show how the volcanoes might have been 
formed by showers of meteors can be made by covering the 
surface of your starboard with a layer of soft clay about 4 inches 
thick, and then throwing clay balls against it. Artificial vol- 
canoes with craters and all will result as shown in Fig. 104. 
Compare this picture with that of Fig. 105, showing the real 
volcanoes on the Moon, and you will see they are quite alike. 










7: S v 



Fig. 105. — Real Volcanoes. 



The volcanoes of California, Japan and the Hawaiian Islands 
are, many of them, still active, while those on the Moon have 
long since become extinct. This is easily accounted for, since 
the mass of the Moon is very small compared with that of the 
Earth, and hence, the Moon has cooled off more quickly than 
the Earth. The result is that while the Earth is yet hot and 
teeming with life and activity, the Moon is cold, and dead and 
silent. 

Seeing the Moon With the Naked Eye. — If you look at 
the full Moon with the naked eye it will appear as a great, sil- 
very-bright disk, and about the same size as the Sun. 



THE MOON, THE EARTH'S DAUGHTER 93 

Look again and yon will see that some parts of it are much 
brighter than others, while another and closer observation will 
show you that the light and shaded parts take on the expression 
of a man's face, as shown in Fig. 106. This is the famous 
Man in the Moon, and once yon make ont the likeness yon will 
never again be able to look the full Moon in the face without 
seeing the man in it. 

When we look at the Moon we always see the same side of it, 
which will be readily understood when we come to the turning 
of the Moon on its axis. As the Moon revolves about the Earth, 
you will see, if you look toward the west 
at the right time of the month, just at 
dusk, a pale crescent of light, and very 
soon after the Sun sets it drops out of 
sight below the horizon. 

A few nights later the Moon will be 
seen, over in the sky toward the east; 
its crescent shape grows into the first 
quarter, and the Moon looks as if it was Fig. 106. — Naked Eye 
split in two. As the nights go by the Soo™ ° F ^ 
Moon waxes until it is gibbous and fin- 
ally the full Moon — with the man in it — stands out round and 
clear and bright. 

It is a good idea at this time, that is, when the Moon is 
full, to make a drawing of her face, and the best time to do it 
is shortly after twilight, for later in the evening the Moon is so 
bright it is hard to see the details. After this the Moon begins 
to wane; it again becomes gibbous; then reaches its last quarter 
later only a crescent can be seen, and she finally disappears. 

At other times when the crescent is bright the whole dark 
disk of the Moon can be seen glowing dimly with a reddish, 
copper color, and this is called the old Moon in the new Moons 
arms. This copper-colored glow is the Earth-shine on the 
Moon, that is, the sunlight on the Earth, which is reflected to 
the Moon and back again to us. 

On one side of the Moon you may be able to see a dark oval 




94 



THE BOOK OF THE STARS 



spot which is marked Grimaldi on the maps of the Moon. Gri- 
maldi is a great plain, having nearly 14,000 square miles in it, 
with mountains flanking it on the sides. This is another good 
eyesight test, for it takes a mighty sharp eye to see it without 
a glass. 

These and a dozen other interesting things on the Moon 
can be seen without a telescope. 

The Motions of the Moon. — The Moon turns round on its 
axis once every month and it also revolves round the Earth once 
every month, so that the Moon's day and year are of the same 




^? 0N '5 OR6fT 



Fig. 107. — The Experiment Showing How One Revolution op the 
Moon round the Earth Makes it Turn Once round its Axis. 



length just like Mercury and Venus, and this is the reason that 
one side of the Moon is always turned toward the Earth, as 
you will see if you look at her through a glass. 

A simple experiment will show the cause of this: Place an 
apple, which we will call the Earth, on the bottom of an in- 
verted glass on a table, and draw a chalk circle a foot in 
diameter around it. Next, take a tablespoon to represent the 
Moon, and hold it upright with the point of its bowl on the 
chalk line and with the bowl turned toward the apple, as shown 
in Fig. 107. Now, draw the spoon round the circle, turning 
it in your fingers so that the bowl is always toward the 
apple. 



THE MOON, THE EARTH'S DAUGHTER 95 

It is easy to see that in order for the bowl of the spoon to 
be turned toward the apple during all of its travels round the 
chalk circle the spoon must also turn once round on its own 
axis, and this is the reason we always see the same side of the 
Moon. 

The Moon's Phases. — Since one side of the Moon is always 
turned toward the Earth, it is clear that this is the only side 

SLICE CUTOUT^ 
HERE 



THE SLICE 




SIDE VIEW MmSW SLICE CUT 

OF APPLE m HJBHH! OUT HERE 



TOP VIEW OF APPLE 

Fig. 108. — Apple Cut to Show Crescent. 

we can ever see, and, further, we are only able to see all of this 
side part of the time. 

The different aspects we get of the Moon as it revolves round 
the Earth are called the Moons phases; and each phase has a 
name, as the new moon; the first quarter; the full moon, and 
the last quarter. 

Between the new Moon and the first quarter, and between 
the last quarter and the new Moon only a crescent, or sickle-like 
edge of the Moon, can be seen; while between the full Moon 
and last quarter the Moon is gibbous (pronounced gib'-us and 
meaning swelled, or shaped like a football). 

If you will look at the picture, Fig. 108, and the diagrams, 
Figs. 109 and 110, and do the experiment which follows, the 
way the phases of the Moon are made will be perfectly clear. 

The picture, Fig. 108, shows an apple from which a thin 



96 



THE BOOK OF THE STARS 



sector or slice has been cut. The lower picture shows the stem end 
of the apple and from this point of view the part where the slice 
was cut out looks wedge-shaped. This is the view of the Moon 
shown in Fig. 109, if we could look down on it. 

Now turn the apple on its side and the place where the slice 
was cut out can be seen from the stem to the blossom end of 



SUN 



SUN 



SUN 




FULL MOON 

Fig. 109. — Diagram Showing How the Moon's Phases Are Made. 



the apple when it takes on a crescent form. This is the view 
of the Moon we really get between new Moon and its first 
quarter, as shown in Fig. 110. 

The diagrams, Figs. 109 and 110, show the Earth in the 
center of the Moon's orbit and the Moon is pictured in eight 
positions, as it moves round the Earth, one for each phase, while 



THE MOON, THE EARTH'S DAUGHTER 97 

the sunlight falling upon the Earth and the Moon is shown by 
streamers of light from the Sun above. 

The diagram, Fig. 110, shows how the sunlight falls on the 
Moon, but you must always keep in mind that only that part 
of the Moon which is in the sunlight and which is also inside of 
the line of its orbit can be seen from the Earth. 



SUN 



SUN 



SUN 




FULLMOOt* 

Fig. 110. — Diagram of the Moon's Phases as We See Them. 



Starting now with the new Moon, Eig. 109, it will be seen 
that the Moon is directly between the Earth and the Sun and 
hence that part of the Moon toward the Earth is in the shadow. 
Now, since the eye can see nothing in the s'ky which is not 
shining, and since the Moon rises and sets at the same time as 
the Sun, we cannot see it. As the Moon moves on round the 



98 THE BOOK OF THE STARS 

Earth in the direction of the arrow and while half of it is in 
the light and half of it is in the shadow as before, from our posi- 
tion we are now able to see a narrow strip of its bright surface 
which in Fig. 109 is shown as a wedge, but since we are 
looking at it from an angle we see it as a crescent, as shown in 
Fig. 110. 

The Moon having reached its first quarter sets at midnight 
and from the Earth half of its bright surface can be seen, 
which of course is only one quarter of the Moon's whole surface. 
The next phase of the Moon is when nearly all of its bright side 
can be seen. This is the gibbous phase and the Moon then 
seems to be about the shape of a football. 

After the gibbous phase the full moon appears and this takes 
place in that part of the sky opposite the setting Sun. When 
the Moon is full it shines all night and does not set until sun- 
rise. 

From this time on the bright part of the Moon which we 
can see grows less and the gibbous phase again takes place. 
Soon the Moon reaches its last quarter and gradually the 
straight rough edge is hollowed out and another crescent is 
formed. The Moon is now in the east and the horns of the 
crescent point to the west, just opposite to the direction the 
horns of the new Moon pointed. The horns of the new and old 
crescents always point away from the Sun and this also is a 
good thing to remember. 

To show how the Moon changes its phases perform the fol- 
lowing simple experiment: Peel half an orange and push a 
knitting needle through its center and let this be the Moon. 
Your eyes will serve for the Earth and a lighted lamp will make 
a very good Sun, all of which is shown in Fig. 111. 

Hold the orange by the knitting needle well out from your 
body with the peeled side toward you, and in such a position 
that the orange will be between your eyes and the lamp. The 
side of the orange toward you will be in the shadow and this 
represents the new Moon. 

Now slowly turn your body round to the left and always 



THE MOON, THE EARTH'S DAUGHTER 99 



hold the orange with the peeled side toward you. You will see 
that the light from the lamp striking the orange forms a cres- 
cent with its horns pointing away from the light. 

Keep on turning, a little at a time, and soon a quarter of 
the orange will reflect the light and this is like the first quarter 
of the Moon. When you have turned nearly halfway round 
nearly half of the orange will shine by the reflected light of the 
lamp and you will have a fair example of the gibbous Moon. 

When you have turned your back to the light hold the orange 
above your head so that 
your shadow will not hide 
it; now half of the orange 
— the half that is peeled — 
reflects the lamp-light and 
represents the Moon when 
it is full. 

As you keep turning 
round the amount of light 
reflected by the orange, 
which you can see grows 
less and less, the bright part 
at first being gibbous, then 
the last quarter is seen, 
after that a thin crescent, 
and finally when you have 
turned completely round the orange is again between your eyes 
and the light, hence it can no longer be seen, and the new 
Moon phase is again at hand. 

The Harvest and Hunter's Moon. — You will remember 
that on September 21 the days and nights are equal and this is 
called the Autumn Equinox. The full moon that falls nearest 
to September 21 is called the Harvest Moon as it rises at nearly 
the same hour for several nights in succession and this makes 
the moonlight evenings unusually long. The Hunters' Moon 
follows the Harvest Moon. 

How the Moon Makes the Tides. — When we are at the sea- 




Fig. 111. — Boy, Lamp and Orange 
Showing Phases of Moon. 



100 



THE BOOK OF THE STARS 



o 



HIGHiTIDE 



shore we soon see that there is a regular rise and fall of the 
ocean. 

This rise and fall of the waters is called the tide, and if we 
note the time when the waters have reached the highest point — 

which is called high tide — we 
MOON will find that a little over six 

hours later the waters have 
reached their lowest point — or 
low tide. 

Before the tide has reached 
the high point again another 
six hours and some minutes 
have passed so that from one 
high tide to another high tide 
12 hours and 25 minutes have 
elapsed. These tides are 
chiefly caused by two forces 
acting on the oceans, one be- 
ing the attraction of the Moon 
for the Earth, and the other 
being the centrifugal force set 
up by the Earth's motion round 
its axis. 

The effect of the Moon's 
attraction for the Earth is to 
pull the water of the ocean on 
the side of the Earth nearest 
it, and this forms a bulge, or 
great wave, while on the other 
side of the Earth the centrif- 
ugal force acts stronger on the water than the attraction of 
the Moon, and this pulls the water in the opposite direction. 
Thus two tidal waves are formed at the same time, one on 
each side of the Earth, as shown in Fig. 112. 

Since the Earth revolves round its axis once in 24 hours 
these tidal waves are carried with it and as there are two tidal 




HIGH TIDE 

Fig. 112. — Attraction of the 
Moon Causes the Tides. 



THE MOON, THE EARTH'S DAUGHTER 101 



waves each day there are two high tides 
and two low tides at every place on the 
ocean, but these are chiefly noticeable 
on the coasts. Fig. 112 shows the posi- 
tion of the Moon and the Earth, while 
the wavy lines aronnd the Earth repre- 
sent the oceans. 

Spring Tides and Neap Tides. — 
Not only does the Moon's attraction 
cause the tides, but the Sun's pull on 
the Earth also produces tides. 

When the Sun and Moon are in a 
line with the Earth they pull together 
and the tides are raised very high and 
they fall very low, and these high and 
low tides are called spring tides. 

Since we 



NEW « MOON 
HIGHEST TIDE 




HIGHEST TIDE 



Fig. 113. — How Spring 
Tides Are Formed. 



HIGHEST TIDE 




HIGHEST TIDE 



FULL 



i 

o 



MOON 



Fig. 114. — How Spring 
Tides Are Formed. 



have either new 

Moon or full Moon, when the Sun, Earth 
and Moon are in a line, the spring tides 
occur at these times, or twice every 
month. Figs. 113 and 114 show how 
the spring tides are formed. 

When the Moon is at its first quarter, 
as in Fig. 115, or in its last quarter, as 
in Fig. 116, the Sun's pull and the 
Moon's pull oppose each other and the 
tides are lowest. These low tides, which 
take place twice a month, are called 
Neap tides. 

A Trip to the Moon. — Many stories 
have been told about imaginary trips to 
the Moon and what the adventurers saw 
after reaching their destination. 

Our story is made up of facts and 
the only thing we shall imagine is that 



102 



THE BOOK OF THE STARS 



we have made the trip and set foot somewhere on the Moon. 
Having performed this mental somersault we shall carefully 
leave out all the hard questions about living there without air 
and water, for this is a pleasure trip and we don't want to spoil 
the fun with details. 

On landing after our 240,000-mile trip we find that there is 
not only neither air nor water, but that the Moon is stone cold ; 
even when the Sun shines on it, it is freezing cold, while the 




ft* QUARTER!* 



Fig. 115. — How Neap Tides Are Formed. 



temperature drops to 500 degrees below zero when the Moon's 
night comes on. 

Our next observation will probably be that we feel much 
lighter than we did on Earth and we are lighter in the very 
nature of things, for the weight of bodies on the Moon is only 
one-sixth as much as they are on the Earth. This is due to the 
Moon being so small and light that gravity has only one- 
sixth as great an attractive force there as it has on the Earth. 

Supposing we still retained on the Moon as much strength 
as we had on the Earth; then every time we took a step we 
would cover a distance of 15 or 20 feet; if we jumped we would 
sail through space with the agility of a Harlem goat, and if 



THE MOON, THE EARTH'S DAUGHTER 103 

we played ball and batted the sphere fairly it would shoot off 
a quarter of a mile and go twice as far from the home plate. 

Since there is no air on the Moon, in order to see one an- 
other the Sun would have to shine directly on us, and if by 
any chance we should get into a shadow we would be as com- 
pletely lost to view as if we had fallen into one of the craters, 
for a shadow on the Moon is as deep and black as the darkest 



o OR0INARY LOWTIDE £ 



o 
a 



O ORDINARY LOWTIDE O 

Fig. 116. — How Neap Tides Are Formed. 

night you ever saw on Earth. Shadows as we know them 
on the Earth are always softened, for the air scatters the 
light. 

Nor would it do us any good to cry out or whistle, for, 
since sound waves are carried by the air, and since there is no 
air on the Moon, all our efforts to make ourselves heard would 
be useless, even if we were only a few feet from each other. 
The Moon is just as silent and cold and still as it looks, for, 
though it serves the Earth well as a mirror to reflect the Sun's 
light, it is, after all, only a great, burned-out cinder. 

Looking at the sky at night from the Moon, we are sur- 
prised to find how much bigger and brighter the stars seem, 
and how many more of them can be seen, than from the Earth. 



104 



THE BOOK OF THE STARS 



Here we see as many with the naked eye as we could see from 
the Earth with a three-inch telescope. 

The Earth itself is seen like a mighty Moon — a Moon as 
bright as 13 of the Moons we are calling on, and so large is it 
that we can see, not only the continents and oceans, but the 



*>"?.* ./SSL'*?- >^li -*> • "f^e^ssufriH.^-. •*—»>. *•* <•**£% **"**7^^^^^fi>^^^^ 








Fig. 117. — View of the Earth from the Moon. 



polar ice caps and the plains and the mountains as well, as shown 
in Fig. 117. 

Watching the Earth from this new viewpoint, we see it turn 
on its axis every 24 hours and going through all the phases — 
crescent, quarter, gibbous and full, and back to crescent again, 
just as the Moon does when we see it from the Earth. 

More curious than the Earth is the view we get of the Sun 
from the Moon, the lack of air making the seeing so good that 
the spots on the Sun, the fiery prominences and the thin corona 
can all be easily seen with the naked eye. 

When the Moon is new the whole half of the Earth that is 



THE MOON, THE EARTH'S DAUGHTER 105 

turned toward the Moon is sunlit and by its reflected light we 
can easily read our time-card — for we must get back to Earth 
again and either write a book or lecture about the wonders we 
have seen. 

The Moon and the Weather. — We have seen in Chapter III 
that our weather is entirely dependent on the Sun. Still it is 
believed by many persons to-day that the Moon has also some- 



12 MIDNIGHT 



EAST 




WEST 



Fig. 118. — Telling Time by the Moon. 



thing to do with the changes in the weather, just as it is the 
cause of the tides. 

Hence there have been handed down to us a large number 
of old sayings to show what the weather will be during certain 
phases of the Moon. But it has been proved by records kept of 
the weather that the Moon has nothing whatever to do with it. 
For this reason no reliance is to be placed in any forecast of 
the weather which is founded on changes of the Moon. 

How to Tell Time by the Moon. — After having learned how 
to tell the hour of the day by the Sun you should learn to tell 
the hour of the night by the Moon. 

On some nights this is a very simple thing to do, for when 
the Moon is full it is due south at exactly 12 o'clock midnight, 
as shown in Fig. 118. 



106 THE BOOK OF THE STARS 

Every night before the Moon is full yon will find it due 
south 55 minutes earlier, so that you must subtract 55 minutes 
from 12 o'clock for each day; that is, one day before full Moon 
it is due south at 11 :05 P. M. ; two days before full Moon it is 
due south at 10 :10 P. M. ; three days before full Moon it is due 
south at 9 :15 P. M., and so on. 

After the Moon is full it will be due south 55 minutes later 
every night and then you must add 55 minutes to 12 o'clock; 
that is, one day after full Moon it is due south at 12 :55 A. M. ; 
two days after full Moon it is due south at 1:50 A. M. ; three 
days after full Moon it is due south at 2 :45 A. M., and so on. 

The Moon's day is 27% of our days long. 

The Moon's year is 27% of our days long. 

The Moon's diameter is 2,160 miles. 

The distance from the Moon to the Earth is 240,000 miles. 



CHAPTEE YII 



OTHER THINGS IN THE SKY 



Seeing an Eclipse. — The word eclipse is taken from the 
Greek and means to fail to appear. 

In starcraft, when the Earth passes across the Sun, and the 
Moon is hidden in its shadow, we say that it is an eclipse of the 
Moon; or when the Moon passes across the Sun and covers it 
we say that there has been an eclipse of the Sun. 

How eclipses of the Sun 
and of the Moon are caused 
can be shown by a very sim- 
ple experiment and you 
ought to make it. 

An Eclipse of the Moon. 
— First let us suppose it is 
the Moon which is eclipsed 
by the Earth. All that is 
needed to show how this is 
done is a lighted lamp on a 
table and an apple with a 
knitting needle through its 
center. Let the flame of 
the lamp represent the Sun, 
your head the Earth and 
the apple the Moon. 

Hold the apple by the knitting needle in a line between your 
eyes and the flame and turn round just as you did in the experi- 
ment showing the phases of the Moon. When you have turned 
halfway round the apple will be in the shadow of your head, 
when the apple is eclipsed, as shown in Fig. 119. 

107 




Fig. 119. — Eclipse of the Moon by 

"* the Earth (Experiment). 



108 



THE BOOK OF THE STARS 



This is just what happens when the Earth gets between the 
Sun and the Moon and all these bodies are in a straight line, 




Fig. 120. — Moon Eclipsed by the Earth (Diagram). 



as shown in Fig. 120; the Moon will then be in the shadow of 
the Earth, and thus it is that the Moon is eclipsed. 

If the Sun, Earth and Moon were always in a straight line 

with each other, every 
time the Earth passed 
between the Sun and 
the Moon the latter 
would be plunged into 
the Earth's shadow and 
the Moon would be 
eclipsed. But the Moon 
does not revolve round 
the Earth so that it 
and the Earth make a 
straight line with the 
Sun every revolution 
for the reason that the 
Moon's orbit is tilted a 
little and hence it is 
only once in a while 
that all of these bodies get in a straight line with each other, 
and when these times do happen then eclipses are produced. 




Fig. 121.— The 



Moon as Seen When in 
Eclipse. 



OTHER THINGS IN THE SKY 



109 



•»*•»•*«» * 



Again when the Moon is eclipsed it is not always entirely 
hidden from view by the great shadow of the Earth, for the air 
on the Earth sends the sunbeams round it so that the shadow is 
never very deep, and for 
this reason the Moon can 
still be seen, as shown in 
Eig. 121. So, then, some 
of these bent sunbeams 
fall on the Moon and are 
reflected from its surface 
back to us and it is then 
that we see the Moon in 
an entirely new light. 

Sometimes during an 
eclipse of the Moon the 
man can still be seen, 
but instead of having a 
bright silvery face he 
will have changed it to 
the copper color of a red Indian. The whole eclipse of the 
Moon often lasts longer than three hours and the time the moon 
is in the deep shadow of the Earth is nearly two hours. 





Fig. 122. — Eclipse of the Sun by the 
Moon (Experiment). 




Fig. 123. — The Sun Eclipsed by the Moon (Diagram). 



A total eclipse is one in which the Moon passes completely 
into the shadow of the Earth, while a partial eclipse is one 
where only part of the Moon is in the shadow of the Earth and 



110 



THE BOOK OF THE STARS 



part of it is in the sunlight. Eclipses of the Moon occur quite 
often and you can look up the time of the next one in your 
almanac. 

Eclipse of the Sun. — When the Sun is eclipsed it is caused 
by the Moon passing between the Earth and the Sun and so 
the light is cut off from the latter. 

To show how this is done all that is needed is to continue 
the experiment with the lighted lamp and the apple which you 

used for the eclipse of the 
Moon. You will remem- 
ber in that experiment 
you were turned with your 
back to the lamp and with 
the apple held in front of 
you. 

Now to show how the 
Sun is eclipsed by the 
Moon keep on turning 
round until you face the 
lighted lamp with the ap- 
ple in between and in a 
straight line with your 
eyes and the flame, as 
shown in Fig. 122. 

Again you will find 

that the side of the apple 

nearest you will be in a 

deep shadow, though usually it can still be seen, and though 

you can see the light all round the apple yet you cannot see 

the flame. 

This is exactly what takes place when the Moon gets be- 
tween the Earth and the Sun and all of these bodies are in a 
straight line, as shown in Fig. 123; the Moon will then cover 
up the Sun and the shadow of the Moon will fall upon the 
Earth in a circle about 100 miles in diameter, as shown in 
Fig. 124. It is thus that the Sun is eclipsed. 




Fig. 124. — Total Eclipse of the Sun, 
Showing Path of the Sun. 




Fig. 125. — Total Eclipse of the Sun, from Photo. 




Fig. 126. — Annular Eclipse of Fig. 127. — Partial Eclipse of 

the Sun. the Sun. 



Ill 



112 



THE BOOK OF THE STARS 



As the Moon is traveling round the Earth and the Earth is 
turning round on its own axis, the Moon's shadow moves across 
a path or trail that is only about 100 miles wide, and it moves 
very fast, too, for it usually takes less than five minutes for 
the Moon to sweep over the face of the Sun. 

There are three kinds of eclipses of the Sun. The first is 
called a total eclipse, and this takes place when the Moon covers 
the entire face of the Sun, as in Fig. 125. 

The second is called an annular eclipse and this takes place 
when the Moon does not completely cover the Sun but leaves a 
bright ring exposed, as shown in Fig. 126. The reason the 
Moon covers the Sun completely during a total eclipse and does 
not cover all of it during an annular eclipse is because the 
orbit of the Moon around the Earth is not a perfect circle, and 
so sometimes the Moon is nearer the Earth than at other times 
and this makes the Moon seem larger or smaller, as the case 
may be. 

The third kind is called a partial eclipse. If we are not in 
the direct path of the shadow of the Moon we may see the Moon 
pass over only a part of the Sun, as shown in Fig. 127. 

The only total eclipses of the Sun which can be seen in the 
United States in the next 30 years are the following: 



Date of Eclipse 


Time of Total Phase 


Course of Moon's Shadow 


1918, June 18, 


2 minutes 


Oregon to Florida 


1922, Sept. 2, 


6 minutes 


Pacific Ocean, U. S. & West Indies 


1923, Sept. 10, 


3 minutes 


U. S. & Atlantic Ocean 


1930, April 28, 


2 seconds 


U. S. & Canada 


1945, July 9, 


1 minute 


U. S., Canada, Scandinavia and 
Russia 



Note: The eclipse of 1930 will be an annular eclipse. 



Finding a Comet. — To the naked eye a great comet looks 
like a bright star with a long, glowing tail. In the long ago a 
comet was called a hairy star, for the early Greeks pictured the 
tail of a comet as being made of long hair and so from their 
language we get the word comet, which means hair. 



OTHER THINGS IN THE SKY 



113 



A comet is really made up of three parts, which are, (1) a 
bright head or core, called a nucleus, and this is covered with 
(2) a layer of hazy light, called a coma, to which there is at- 



^&s^?s&i&& 



' L TAIL— —- . ~ ~ - 






NUCLEUS 

Fig. 128. — Comet Showing Nuclei; s, Coma and Tail. 



tached (3) a luminous tail, all of which is shown in Fig. 128. 
The nucleus of a comet is formed of a bunch of stones and 
pieces of iron, all widely separated and which are held together 
by attraction as they speed through space. As a comet nears 
the Sun it begins to get hot and to 
throw off burning gases, which 
make up its coma, and these 
bright gases streaming along form 
its tail. 

There are several ways in 
which a comet can be told from 
the planets. In the first place, 
new comets, that is, comets which 
have never been discovered before, 
appear suddenly and in any part 
of the sky, though they may be 
very dim at first, and after a while 
they fade away, sometimes never 
to return again. 

Second, they shine chiefly with 
their own light like the stars; 
third, they do not travel in small 
circles around the Sun like the planets ; but the paths they take 
are either long ovals, called ellipses, or great curves whose ends 
never meet, called parabolas and hyperbolas, as shown in Fig. 
129; fourth, they do not travel through space in a line with 




Fig. 129. — An Ellipse, Para- 
bola and Hyperbola. 



114 



THE BOOK OF THE STARS 



the planets and Sim, but shoot in and out of our solar system 
from and to every direction; and fifth and last, they travel at 
enormously high speeds. 

Now, a comet, however great it may grow to be, never bursts 
into view, big, bright and beautiful, but when one is found it is 
usually seen as a little, dim patch of light, and it would quite 




\ 






^ 



Fig. 130. — Head and Tail of Comet Do Not Obey~the Same Laws. 



likely be mistaken for a nebula,, if it did not move along so 
swiftly. 

A comet can be told by its movement and its movement can 
be plotted in the same way I have described for plotting the posi- 
tion of a planet in Chapter IV; and so, if you see a dim, little 
ball of light in the sky and find that it changes its position 
when compared with the fixed stars near it you may guess that 
you have discovered a comet. 

The next thing you should make sure of is, that you have 
not found one of our old familiar friends, the planets. If it 
is really a great comet coming toward the Sun, it will grow 
larger and brighter every night, and you will soon be able 



OTHER THINGS IN THE SKY 115 

to see its tail, which, is the real earmark of a really truly 
comet. 

When a comet is nearest ns its head will shine far brighter 
than any of the planets, and its great tail, millions of miles in 
length, will spread out in a glowing arc and light up the whole 
sky. 

When this time comes a comet is by far a greater sight to 
the naked eye than it is when seen through the largest telescope. 




Fig. 131. — Halley's Comet, from Photo. 

You should observe the comet often and carefully, for another 
one may not appear for a long time. 

The nearer a comet gets to the Sun the faster it travels; 
some comets have been known to move a thousand times as 
fast as a rifle-ball, and this is the more surprising when we 
consider that the great, flaming tail goes along with it at the 
same terrific rate of speed. 

The tails of comets do some very strange things; for exam- 
ple we should rather expect the tail of a comet to always follow 



116 



THE BOOK OF THE STARS 



its head like a skyrocket, but while it does so when the comet 
is headed toward the Sun, when the comet is passing round 
and shooting into space the tail turns away from the Sun, and 
this causes it to move ahead of the comet, as shown in Fig. 130. 
This shows that while the head of a comet obeys the laws 
of gravitation, the tail does not do so, but acts as if it was 
electrified like the Sun, when of course it would be repelled by 
it. Fig. 131 is a picture of Halley's comet of 1910. 

Although a great astronomer once said that there are more 
comets in the sky than fishes in the sea, there have only been 
1,000 comets recorded since the beginning of written history. 

Meteors and Meteorites If you 

will look at almost any part of the sky 
on a clear night when there is no Moon 
you will no doubt see a bright flash like 
a rocket. But if you will scan the sky 
during the dark nights of August and 
November you will be very apt to see 
dozens of these shooting stars or me- 
teors. 

Now, meteors, fireballs, shooting 
stars and meteorites are all one and the 
^^&v^y /* '1 ** *A same thing to start with and they have 
their beginnings when some comet goes 
to pieces. 

After a comet breaks up, the pieces 
of stone and iron which form it still 
travel round in the same orbit. Some of these pieces may get 
within range of the Earth's force of gravitation when they are 
drawn to it, and on striking the air they are intensely heated 
by the friction, and if they are small they burn up before 
reaching the ground. 

The smaller meteors burn up almost instantly and the shin- 
ing tails they leave last only a few seconds. Fireballs, which 
are simply large meteors, leave burning trails which can some- 
times be seen for several minutes. Shooting stars are merely 




Fig. 132. — Meteorite 
of Iron Etched with 
Acid. 



OTHER THINGS IN THE SKY 117 

meteors which are not very bright, while meteorites are meteors 
which have fallen to the Earth before they have had time to 
burn up. 

Many meteorites have been found, but ninety-five out of 
every hundred are of the stony kind, the others being of the 
iron kind. The way to tell a meteorite from a common stone is 
by examining its surface. A true meteorite is covered with a 
black, shiny, burnt crust, caused by the intense heat to which it 
was subjected as it fell through the air. The test for an iron 




Fig. 133.— The Milky Wat. 

meteorite is to grind and polish a part of its surface and then 
cover it with a dilute solution of nitric acid, when markings 
like those shown in Fig. 132 will be etched upon it. 

The Milky Way. — You have, no doubt, often seen on a clear, 
dark night, a wide, ragged band of light stretching from the 
northern sky across the celestial equator and beyond. This 
band of light is the famous Milky Way. 

If, as you were looking at the Milky Way, the Earth could 
be moved from under you and you were left standing in space 
alone so that you could see in every direction, you would find 
that the band formed a complete ring round the sky. 



118 THE BOOK OF THE STARS 

To the naked eye the Milky Way seems to be made up of 
mists of matter as thin as the stuff of which comets' tails are 
made. There are some patches, though, that are very bright, 
but look at them as long as you will with the naked eye nothing 
more can be seen than just a milky patch of hazy white, as shown 
in Fig. 133. 

With a very small telescope, however-, this band of luminous 
matter will be instantly changed into thousands of stars, all 
separate and distinct, and some of these stars will look about 
as large as the stars of the Pleiades when these are seen with 
the naked eye, while others will shine as brightly as Venus or 
Jupiter when they are nearest to the Earth. 

These bright patches, then, which form the Milky Way, are 
really groups of stars or star-clusters, and when some of these 
clusters are photographed through a telescope as many as 15 or 
20 thousand stars can be counted, while the real number of stars 
that lie beyond and which cannot be seen is past all calculation, 
and, just think of it, every one of these stars is a Sun as large 
or larger than our Sun ! 

Those who have made a deep study of starcraft tell us that 
our Sun is one of the stars of the Milky Way, and since the 
other fixed star that is nearest to us, which is Alpha Centaurus, 
is 25 trillion miles away, and Sirius, the Dog Star, which is the 
brightest star in the whole sky, is three times as far away as 
Alpha Centaurus, we may gain some slight idea of the enormous 
distances of the fainter stars that make up the Milky Way. 

The Nebulae. — Unlike the bright, cloud-like patches in the 
Milky Way, and which the telescope shows to be formed of sepa- 
rate and distinct stars, are the faint misty spots in the sky 
called nebulce (or nebule). 

Xow the nebulae give us a clew as to how the stars were made, 
and how other stars are now being made, for it is believed that 
the nebulae are the raw material which, when set in motion, pro- 
duced heat and took on form and became Suns and planets like 
our own solar system. 

Two ideas of what these nebulae are made of have been worked 



OTHER THINGS IN THE SKY 119 

out. The first concludes that they are formed of hot gases and 
particles of other matter ; and the second takes them to be small 
solid bodies all very far apart and moving round tiny orbits 
like a lot of little planets. 

There are a few of these nebulae which can be seen with the 
naked eye ; one of these is the Great Nebula of Orion,, and if you 
will look at Orion some night and draw an imaginary line a 
little below his belt and toward the east you will be able to 
find it. Another nebula that is bright enough to be seen with 
the naked eye is the Great Nebula in Andromeda. Both of 



.%: Of. . ■■■': S : - 

RIN&' NEBULA GREAT '" i * 




IN LYRA NEBULA IN ANDROMEDA 


SPIRAL- NEBULA 



Fig. 134.— Different Forms of Nebula. 

these nebulae are good tests for eyesight. Fig. 134 shows some 
of the different forms of nebulae. 

The Making of the Stars. — To explain how our Sun and 
the planets were made, as well as all the other stars in the uni- 
verse, two ideas have been worked out, and although these are 
quite unlike in many ways, yet both start out with the nebulae. 
The first of these is called the nebular hypothesis and the other 
and later one is called the planetesimal hypothesis. 

The Nebular Hypothesis. — We have found out what nebula 
is believed to be and we should next understand exactly what 
the word hypothesis means. An hypothesis is an idea worked 
out so that there is a fairly good chance of its being true. 

The nebular hypothesis, then, is an idea that has been worked 
out from what nebulae are believed to be and what is known of 
the mighty forces of nature, and these when taken together 



120 THE BOOK OF THE STARS 

seem to show that all the things in the sky — stars, planets, 
moons, comets and meteors — are made of nebular stuff. 

The neublar hypothesis says that when the nebular matter, 
or star stuff of which the planets were made, was thrown off into 
space by the centrifugal force of the Sun, they were all whirled 
away in the same plane, turning on their own axes and traveling 
round the Sun in the same direction. 

The Planetesimal Hypothesis. — A later idea is called the 
planetesimal hypothesis. Planetesimal means little planet, and as 
we know already what hypothesis means, by coupling the two 
words together we may easily guess that it is an idea worked 
out which accounts for the making of solar systems out of little 
planets. 

The planetesimal hypothesis also starts with a great nebula, 
but instead of taking the nebula to be made of hot gases and 
like particles of matter, it says that the nebula is already formed 
of meteors which travel in orbits of their own and hence are 
really little planets. 

The meteors, or little planets, making up the nebula, attract 
each other, like all other bodies, and when they get close enough 
they are drawn together and dense masses of matter, or cores, 
are built up. The largest core is seen in the center of a spiral 
nebula, and as it becomes more compact it grows hotter and a 
Sun is made, while the other and smaller cores turn round it 
and attract little planets to them. And so the cores grow in 
size, and with more and more weight bearing toward their cen- 
ters the gases are forced out and these make the air and water. 

It is in this manner that the planetesimal hypothesis explains 
how the Sun, planets and Moons of the solar system are made. 



CHAPTER VIII 
SEEING THE STARS 

How the Stars Shine. — A burning match, a candle, an oil 
or gas flame, the Sun, comets and meteors all give out light and 
heat in exactly the same way, though they may seem to do so 
quite differently. 

When you strike a match the friction makes enough heat to 
light the chemicals of which the head is formed and the burning 
gases light the splint which in turn generates more gases from 
the wood and these give out more light and heat. 

When you light a candle the heat melts the wax which is 
then drawn up the wick, the burning gas around the wick pro- 
duces more gas and the gas keeps the flame going. In the case 
of an oil lamp the oil, which is already a fluid, is drawn up by 
the wick, where it is changed into gases, and light and heat 
result as in the candle. The oil lamp is, then, a step ahead of 
the candle, for the solid wax is replaced by the fluid oil. 

In the gas light the gas, which is made of coal or other 
matter, is forced out of the jet under pressure and this gives a 
bigger and better flame than the oil lamp ; and, as the oil lamp 
is better than the candle, so the gas jet is an improvement over 
the oil lamp. 

Now the Sun is so large and the burning gases are so hot 
that when solid matters, such as iron and other metals, are 
thrown out by the great eruptions from the inside they are not 
only melted but they are instantly changed into gases and the 
burning gases send out both light and heat. 

When a comet comes close enough to the Earth to be seen it is 
then close enough to the Sun so that the light and heat of the 
Sun cause some of the gases of which the nucleus of the comet 

121 



122 THE BOOK OF THE STARS 

is formed, to become white hot; as a comet gets closer to the 
Sun the solid matter of the nucleus, such as sodium — which is 
a kind of salt — iron and other things are changed into gases 
and these burn fiercely. 

While we can see the light of a comet we cannot feel its 
heat, for a comet is too small to send its heat waves through such 
a great distance. 

Just as a match is lit by striking it, so meteors are set on 
fire by striking the air. Meteors are made up of the same kind 
of matter as c6mets and when these shooting stars come within 
the attraction of the Earth the friction caused by the meteor 
rubbing against the air is so great that an intense heat is pro- 
duced and the gases burst into flame. 

If a meteor is small it is entirely burned up before it reaches 
the Earth and all we see of it is a bright streak of light. If a 
meteor is large enough only the outside of it is burned and it 
will, in consequence, reach the Earth, when it becomes, as ex- 
plained in the last chapter, a meteorite. 

Meteors and meteorites produce a very bright light, burning 
as they do in the oxygen of our air, and though they are very 
close to us they are so small we cannot feel any heat sent out by 
them. 

We have said that when a match is struck the friction pro- 
duces heat and that when the wax of a candle, the oil of a lamp 
or the gas of a jet is burned they produce light and heat, and 
this is also true of the blazing Sun, the fiery comets and the 
burning meteors. 

Where there is light there is usually heat and turn about 
where there is heat there is light if the temperature is high 
enough. Heat is produced before light, but the two are nearly 
always found together and they are so much alike they might 
be called the Siamese twins. 

What Heat and Light Are. — We know that both heat and 
light are caused by burning gases, but let's get a little closer 
and find out just how and why gases which are burning send 
out heat and lisrht. 



SEEING THE STARS 123 

Now gases are formed of particles of matter called atoms 
and these atoms are very small but they have a certain size 
and weight according to the substance they form. When these 
gases are cold the particles, or atoms, are quiet, but when they 
are heated to a high temperature they are thrown into a violent 
state of motion and vibrate to and fro a given number of times 
per second, or frequency, as it is called, according to the sub- 
stances they are made of. 

The next question in order is what makes the particles, or 
atoms move, or vibrate and the answer is combustion, which 
means the process of burning. Combustion, or burning is a 
chemical action and can be explained by saying that it is the 
combining of a substance with oxygen, but many substances 
like hydrogen will burn if they are heated without being com- 
bined with oxygen. 

The only difference between heat and light is that of wave 
length as we shall see presently, and the length of heat waves 
and of light waves depends entirely on the rapidity with which 
the atoms vibrate, or the frequency of vibration, as it is called. 
If the atoms of gas move slowly heat is sent out and if the 
atoms move rapidly the heat grows more intense and light is 
radiated. 

When the atoms of a burning gas vibrate just fast enough 
to produce light the color of the light is red; when the atoms 
vibrate still faster the color of the light is green and when the 
atoms vibrate very fast the light sent out is violet, so we see 
that not only do the vibrating atoms send out light but that 
the rapidity, or frequency with which they vibrate makes, or 
determines, the color as well of the light which is sent out. 

One thing more: the rapidity of the motion, or vibration, 
of the atoms of a gas depends entirely on the substance which is 
being burned, so that certain substances when burning always 
produce certain colors. (See Chapter XII, What the Stars Are 
Made Of.) 

How Heat and Light Travel. — While the little motions or 
vibrations, of the particles, or atoms, of gas forming the flame of 



124 



THE BOOK OF THE STARS 



a candle, the Sun, and other heat and light givers could go on 
just the same we could not feel their heat or see their light 
without something or some kind of a substance which would 
connect them with our bodies and our eyes, like a wire connect- 
ing a push button with an electric bell. And there is something 
which connects us with the most distant stars and that some- 
thing is called the ether. 



' ^Ifeg^^^—Jf: 




*^<>A*« * 



Fig. 135. — Ripples or Waves on Water. 



To show how these little movements, or vibrations set up 
by the atoms of a flame impress us as heat or light do at a 
distance we will begin with a simple experiment to show what 
the ether is and how it acts. 

If you will stand on the edge of a pool of water and throw 
a stone into the middle of it you will see a little ring-like rip- 
ple, or wave start out from the point where the stone struck the 
water; this ripple, or water wave will continue to grow larger 
and larger in diameter and weaker and weaker until it reaches 
the edge of the pond, as shown in Fig. 135, or if the pond is 
very large the waves will die out before they reach the edge. 

Again, if you toss a number of stones into the middle of 
the pond one after another a series of ring-like waves will 



SEEING THE STARS 125 

follow from the center of the pond where the stones strike the 
water to the edge of the pond, or until they die out. 

In the same manner if a bell is struck by a blow of its 
tongue, ripples, or waves in the air will be sent ont all around 
the bell. These waves in the air are called sound waves, but 
they are, after all, only air waves. 

When a bell is struck the rim of the bell moves forth and 
back, first in one direction and then in the other, as shown in 
the diagram, Fig. 136, and we call these little movements of the 

bell vibrations. The movements are so „ 

small that you cannot see them, but if you J^ -l"^v 

put your finger on the bell you can feel £i \\^ 

them. /// \]S 

Although the vibrations of a bell are \ I ' j // 

very small they are powerful enough to s ^^ ^r 

set up ripples, or waves in the air as *<— " ^7 

shown in Fig. 137, and when these air FlG> i 36 ._ V ibration 
waves or sound waves strike the drum of of a Bell. 

the ear it vibrates just like the bell and 

the auditory nerve of the ear carries the waves on to the brain 
and we hear the bell ring. 

It must be plain now that if there was no air connecting 
the bell with our ears the bell might keep on ringing and yet 
we could not hear it. 

When the air is set in motion by the vibrations of a bell, or 
any other device for producing from 32 to 40,000 vibrations 
per second, we can hear it, and when the air moves as a mass, as 
when the wind blows, we can feel it. Air forms a layer around 
the Earth that is between 200 and 300 miles thick, but out in the 
great space beyond there is no air. Yet the space is not empty, 
but it is filled instead with a substance called the ether. 

Just as the air is finer than water so the ether is a million 
times finer than the air. It is so fine that it fills up all the little 
spaces between the particles or atoms of water and of the air, 
and it penetrates in between the atoms of the densest metals 
and the hardest glass, and further, and still more wonderful, it 



126 



THE BOOK OF THE STARS 



fills all of the great space in which the planets and the stars are 
placed. 

Now when the particles, or atoms of gas are set in motion, 
or vibration by a flame of any kind, be it a candle or the Sun, 
little ripples or waves are started in the ether and if these 
waves are very short they affect the eye and cause the optic 
nerve to vibrate exactly like the vibrations which are sending 
out the ether waves and these waves are carried to our brains 




Fig. 137. — Sound Waves in the Air Set up by Bell. 



and we see the light. The way in which a flame sends out 
waves in the ether and is received by the eye, is shown in Fig. 
138. 

It takes a ripple, or wave on the water started by the impact 
of a stone about one-half second to travel one foot. A sound 
wave, set up by the vibrations of a bell, or other sound produc- 
ing device, travels through the air at the rate of 1,090 feet per 
second, while light and heat waves set up by the vibrations of a 
flame, the Sun or other hot body, travel through the ether at 
the rate of 186,500 miles per second. 

It must be plain now that if there was no ether connecting 



SEEING THE STARS 



127 



the flame, or the Sun with our eyes the flame, or Sun might 
continue to send out light and yet we could not see it. 

How the Eye Sees. — If it was not for our ears we could 
not hear a bell ring nor any sound, for though the waves in the 
air might still be sent out we would have no means of receiving 
them ; again if it was not for our eyes we could not see a flame, 
the Sun or any other source of light and, what would be worse, 
we could not see an object by its reflected light, for though 



W \S 





Fig. 138. — Waves in the Ether. 



the waves in the ether would still be sent out we would have 
no means of receiving them. 

The eye is simply a camera on a very small scale, but what 
it lacks in size it makes up by the excellence of its operation. 
If you will set up a sheet of white cardboard on one end of your 
starboard, place a lighted candle at the other end and then hold 
your burning glass between the flame of the candle and the 
cardboard, as shown in Fig. 139, and do all this in an otherwise 
dark room, you will see a picture turned upside down, called 
an inverted image,, of the candle flame on the cardboard. 

To get a sharp picture, or image of the flame on the card- 
board screen you will have to move the lens toward and away 
from the cardboard, and this process is called focusing. If you 
will fix the lens in the front of a light-tight box and place a sheet 
of ground glass in the back of the box you will have a simple, 
though crude, camera. 



128 



THE BOOK OF THE STARS 



The eye has all of the things which the highest priced cam- 
era has and a good deal more, for all of its adjustments are 
automatically made, and you don't even have to think about 
them. 




Forming an Image with a Lens. 



The eye is almost as round as a ball and it can be turned 
a little in its bony socket in any direction. The outer part of 
an eye which takes the place of the box of a camera, is stretched 
round the whole eye like the cover of a baseball, as shown in 




CORNEA 



K OPTIC 
NERVE 



Fig. 140.— The Human Eye. 



Tig. 140. The front part of this cover forms the white of the 
eye, and fitting into the cover and over the lens, like a watch 
crystal in its rim, is the cornea, which is a tough, but trans- 
parent film and protects the iris and the lens. 



SEEING THE STARS 129 

Between the lens and the cornea is a thin disk, or diaphram 
with a hole in its center and this is the iris; the purpose of the 
iris is to let in only a certain amount of light, just like the 
shutter of a good camera. The hole in the iris forms the pupil 
of the eye, and you can see the hole, or pupil, grow larger or 
smaller, just as the eye needs more or less light. 

The lining of the eye is called the retina and this forms a 
screen at the back of the eye on which the light waves in the 
ether project the image of the object at which the eye is looking. 
Instead of being white like our cardboard screen the retina is 
very black. 

The retina upon which the image is formed is connected with 
the optic nerve; in fact, the retina is a part of the optic nerve 
and is covered with a lot of little nerve ends or filaments called 
rods and cones. 

Now when the waves in the ether sent out by the flame of a 
candle, or by the Sun, reach the eye, they pass through the 
cornea, then through the pupil, or hole in the iris, and finally 
through the lens which focuses the waves on the retina and 
forms the image there. 

The different colors of light are caused by waves in the 
ether of different lengths; when very short waves strike the 
retina we say the color is violet; waves a little longer we call 
green and the longest waves which the eye can see form in our 
brains the sensation of red. 

Waves in the ether which are longer than the wave lengths 
the eye can see produce heat and when these waves fall on any 
part of the body the nerves detect them and we call the sensa- 
tion heat. On the other hand waves in the ether which are too 
short to affect the nerves of the eye will impress a photographic 
plate. 

The iris of the eye acts as a self-regulating shutter, which 
makes the hole, or pupil in front of the lens larger or smaller 
according to the amount of light which is needed to see an object 
well. If the light is strong the iris contracts, which means that 
the hole gets smaller and so cuts off some of the light. If the 



130 THE BOOK OF THE STARS 

light is weak the hole gets larger and we say the pupil expands 
and this lets more light through the lens. 

There must also be some means of adjustment to make a 
sharp image, or picture, on the retina, however near or far away 
the object may be from the eye. In a camera this is done by 
moving the lens and the screen closer together or farther apart 
and this is the purpose of the bellows of a camera. 

But the eye has a much finer and quicker adjustment than 
this for distance. The lens is so made that the front part of 
it can bend just as the distance changes. You have only to 
look at an object and the lens is adjusted without the slightest 
effort or knowledge on your part. 

You may wonder how light waves can pass through a sub- 
stance as solid and as hard as glass or through the eye. You 
will remember I told you in the beginning of this chapter 
how ether got into every little space, even in metals and glass, 
as well as that it filled all the great space between the stars. 

We think of glass as being very solid, and it is solid enough 
to keep water or air in a bottle from getting out through its 
pores. But glass and the substance of which the eye is made 
are just about as full of holes as a sieve, but the holes are so 
very, very small you couldn't begin to see them even with the 
aid of a high-power miscroscope, yet they are large enough for 
the ether to run through just as water runs through a sieve. 

When I tell you that waves in the ether which are sent out 
by the light of a candle or the Sun are only about 15 ten- 
millionths to 30 ten-millionths of an inch in length, and that 
the holes, or pores, in the glass and the cornea and lens of 
the eye, and which are full of ether, are much larger, you can 
readily understand that the ether waves which we call light 
can merrily pass through either glass or the eye and that there 
is nothing in the way to stop them. 

To sum up briefly how the stars shine, how light travels 
and how the eye sees we will start with the light of the Sun 
and say 

(1) That the Sun is made up largely of gases, and that 



SEEING THE STARS 131 

(2) These gases are formed of various substances, and that 

(3) The gases are burning fiercely and produce terrific heat, 
which means that 

(4) The atoms or particles which form the gases are in 
violent motion or vibration. 

(5) These vibrations start out waves in the ether which 
travel out into space at a speed of about 186,500 miles per 
second. 

(6) On reaching the eye the waves pass through the lens 
and form a picture or image 

(7) On the retina, or screen of the eye, which is made up 
of the ends of nerves, and these vibrate just as the atoms of 
the gases in the Sun which sent out the waves vibrated, and 
finally 

(8) These nerve vibrations are sent over the optic nerve to 
the brain, where they take on the shape, size and colors of the 
Sun. 

Reflection of Light.— The flame of a match, or a candle, 
an oil or a gas lamp, or Sun, comet or meteor, produces its own 
light, and for this reason these bodies are called self-luminous 
— that is, they are themselves the source of light. 

All other objects which do not produce light, such as an 
apple, a stone, the Earth and other planets and moons are 
called non-luminous bodies. 

Yet these non-luminous bodies can send out light if they 
are lighted up by some self-luminous body. It is well that this 
is so, or else we could never see anything that was not in itself 
giving out light. 

If you will hold an apple or a stone in your hand and let 
the light of a candle or the Sun fall on it you will be able to 
see the apple or stone, and, although you will hardly be able 
to notice it, you will see them by the light which strikes them 
and is turned back, or reflected from their surfaces, as shown 
in Fig. 141. 

If a rubber ball is thrown on the sidewalk it will bounce 
back and this is just the waj light acts when it strikes most 



132 



THE BOOK OF THE STARS 




Fig. 141. — Light Reflected 
by an Apple. 



objects — it bounces back, or, to use the right word, it is re- 
flected. 

When we look aj the surface of the Earth by daylight we 
see the sand and stones, grass and trees, houses and other ob- 
jects by the light which is re- 
flected, or thrown back from the 
surface of these things by the Sun. 
When we look at the surface 
of the Earth by the light of the 
Moon we also see the objects by 
reflected light, but in this case the 
light is twice reflected, for moon- 
light is the light of the Sun fall- 
ing on the Moon and which is then 
reflected to the Earth, where it is 
again reflected to our eyes from the objects it falls on. This 
is the reason moonlight is so pale when compared with sun- 
light. 

Refraction of Light. — When a beam of light 
through glass, water and other trans- 
parent substances, and is bent out of a 
straight line it is said to be refracted. 

Place a spoon in a glass of water, as 
shown in Fig. 142 and it will look as if 
the spoon is broken in two at the point 
where it touches the water. The bend- 
ing of the beam of light will be more 
clearly understood from the drawing in 
Fig. 143. 

If you will look at a star through a 
thick piece of glass and the star seems 
to change its position a little you will 
know that the sides of the glass are not 
quite parallel. 

A prism is a three-sided piece of glass, if we except the 
ends, as shown in Fig. 144. When a beam of light passes 




Fig. 142.— Light Re- 
fracted. Spoon in 
Glass of Water. 



SEEING THE STARS 



through a prism . the prism affects the light in two ways : first, 
it bends the beam, and second, it separates the ether waves, or 
light waves, as they are called, according to their lengths, and 
as color depends on the length of the waves in the ether a 




Fig. 143. — How Light is Refracted. 

prism will show the different colors on a screen and this is 
called the spectrum. It is shown in Fig. 145. 

Lenses are pieces of glass having cnrved surfaces. When 
a beam of light passes through a lens it is also bent out of its 
original direction, or refracted. 

A convex lens, see Fig. 146, is a lens which is thicker in 
the middle than it is at the edges. A convex lens is used for 
magnifying an object; or for 
forming an image so that it 
can be magnified by another 
lens as in a telescope, for form- 
ing an image on the screen 
of a camera, and for bring- 
ing the heat waves of the Sun to a focus, as with a burning 
glass. 

The point where the rays of light are brought together is 
called the focus. You can easily find the focus of a lens by 




134 



THE BOOK OF THE STARS 



holding a sheet of paper, or the hand under the lens and letting 
the sunlight pass through it; where the spot of light is smallest 




Fig. 145. — Prism Forming a Spectrum. 

and brightest the distance of this point from the lens is called 
the focal length. 

A concave lens is a lens which is thinner at the middle than 




LENS 






EDGE OF SIDE VIEW OF 

CONVEX LENS CONVEX LENS 

Fig. 146. — Convex Lens. 



FOCUS 



it is at the edge, as shown in Fig. 147. It is used in small tele- 
scopes and opera glasses to turn the inverted picture formed 



SEEING THE STARS 



135 




EDGE OP 
CONCAVE LENS 



SIDE VIEW OF 
CONCAVE LEvNS 



by the convex lens around so that the object can be seen in its 
right position, as shown in Fig. 151. 

Shadows. — Shadows are useful as well as sunshine, but 
shadows are such common, everyday things it seems almost use- 
less to talk about them; still you may or may not know that 
there are different kinds of 
shadows. 

Of course we all know 
that when a candle or a gas- 
light or the Sun shines on 
an apple or any other 
opaque object — that is, an 
object that will not let the 
ether waves go through it — 
the light is cut off back of 

it and this dark space is called a shadow; this is also true when 
the Sun shines on the Earth, or on any of the other planets or 
their moons. 

There are always two parts to the shadow of an object un- 
less the light is a mere point or the object is very close to the 
screen, or surface on which the shadow falls. The dark part 
of the shadow is called the umbra. The edge of the object 
where the light and shade run together and form a partial 
shadow is called the penumbra and during a total eclipse this 
partial shadow surrounds the dark shadow, or umbra of the 
Earth or Moon. 



Fig. 147. — Concave Lens. 



CHAPTEE IX 
THE SPYGLASS OR TELESCOPE 

The Boy Who Discovered the Telescope. — Spectacles have 
been made and used for nearly a thousand years and the art 
of making lenses is very much older. 

A little over three hundred years ago there lived in Amster- 
dam, Holland, a spectacle maker named Lipperhey, and it is 
said of him that he made good lenses. 

There was apprenticed to this lens grinder a Dutch boy, 
and I am sorry I cannot tell you his name, for he was a boy 
who did things ; but his name is not recorded, which is a shame, 
for if it had not been for this boy Galileo might never have 
had a telescope. 

One day while the boss was out this Dutch boy was stand- 
ing before a window of the shop and he held a lens before his 
eye with one hand and another lens before the first lens with 
his other hand, as shown in Fig. 148. Imagine his surprise 
when the church he was looking at seemed to move much nearer 
to him, that is to say, the image of the church was greatly 
enlarged. 

The boy had made a wonderful discovery — he had discov- 
ered the telescope. When his master returned the boy showed 
him what he had done and it was not long before the great 
Galileo had a telescope and was startling the world by his 
wonderful discoveries of the moons of Jupiter, the rings of 
Saturn, the phases of Venus, the spots on the Sun and a hun- 
dred other wonders of the sky. 

A telescope is an arrangement of lenses in a tube for mak- 
ing the image of a distant object larger on the retina of the 

133 



THE SPYGLASS OR TELESCOPE 



137 



eye, or, as in the case of the fixed stars, for making them 
brighter. 

The word telescope comes from two Greek words, the first, 
tele, which means afar, and the second, scope, which means to 



it 



-jil \C£ 



o 







Fig. 148. — Lipperhey's Boy Discovers the Telescope. 



see, so that telescope means just what we should expect it to 
mean and that is to see afar. 

There are several kinds of telescopes, but there are only 
two kinds I want to make clear to you here; in the first 
kind the eye sees the object just as it is, that is, standing 
right side up, or erect. This kind of a telescope is called a 
spyglass, and is used to look at objects on the surface of the 
Earth. 

In the second kind of telescope the eye sees the object up- 
side down, or inverted, and this kind of telescope, which is 



138 



THE BOOK OF THE STARS 



called an astronomical telescope, is just as good as the other for 
looking at the stars. 

A Pinhole Telescope. — Before describing how to make and 
use real telescopes which have lenses I want to tell you of a 
little scheme to see afar, and though it does not magnify the 
image of the object that is seen 
through it, yet it aids the naked 
eye when you are looking at the 
Sun and Stars. 

To make a pinhole telescope get 
a pasteboard tube about 1*4 inches 
in diameter and 5 or 6 inches long. 
A paper tube for mailing papers 
and sheet music is just the thing 
and can be bought at any station- 
ery store. 

Cut out a disk , or circular piece of cardboard just large 
enough to fit the tube, see Fig. 149, and push a pin point or 
needle through the center to make a small, clean hole. Next, 




Fig. 149. — Disk of Card- 
board for Pinhole Tele- 
scope. 



\SSS ///// 



s 



CARDBOARD TUBE 



IV/V/V/Vy'/V/V/V/'///// / 



/. / ,,,,,?}>>>>}>>>,>}>>}>' 1 ? * r > / 



^ 



CARDBOARD TUBE 




Fig. 150. — Cross Section of Pinhole Telescope. 



The disk must be glued in the tube so that no light can leak 
around the edge. 

If, now, you look at the Sun through the pinhole telescope, as 
shown in Fig. 150, you will get a better view of it than 
if you look at it through a pinhole in the cardboard alone, 



THE SPYGLASS OR TELESCOPE 139 

for the tube shuts out all the other rays of light from the 
eye. 

To improve the seeing qualities of the pinhole telescope 
make the hole in the cardboard disk % inch in diameter and 
cover this hole with a bit of tinfoil. Now make a hole in the 
center of the tinfoil with the point of a needle; this makes 
the edge of the hole sharp. 

A pasteboard tube without the pinhole will also aid the 
naked eye in seeing the Moon and stars, for it shuts out all 
the rays of light around the eye and limits the sight to a certain 
part of the sky; together these things are very good helps in 
observing especially if there are gas and electric lights nearby. 




Fig. 151. — The Telescope (Galileo). 

Haw a Telescope Works. — A real telescope has at least 
two lenses in it; the larger lens is placed in the end of the tube 
nearest the object to be viewed and is called the object glass 
because the light from the object is received by it. 

The smaller lens is placed in the end of the tube nearest the 
eye, and is called the eyepiece, for it is this lens which en- 
larges, or magnifies the image of the object that is thrown 
upon the retina of the eye. 

There are two simple kinds of telescopes; the first is the 
kind that Galileo used for making his great discoveries. The 
kind of lenses used and the way they are placed in the tube is 
shown in Fig. 151. 

In this telescope the object glass is a double convex lens and 
the beam of light which strikes it is brought to a point as in 
the case of a burning glass, but before the light reaches this 
point it is caught up by the double concave lens which forms 



140 THE BOOK OF THE STARS 

the eyepiece, when it is carried to the eye in an erect position. 
An opera glass is simply a pair of these little telescopes, 
joined together so that they can be focused at the same time by 
means of an adjusting screw, as shown in Fig. 152. 

Another simple telescope is formed of two double convex 
lenses. As in the telescope just described 
the larger lens, or object glass, is placed in 
the end of the tube nearest the object to be 
viewed and the smaller lens, or eyepiece, is 
placed in the tube nearest the eye. 

In this telescope, though, the eyepiece 
Fig 152.— Opera * s a double convex lens and while a larger 
Glasses. image is formed in the eye it is inverted, 

or upside down, so that this kind of a tele- 
scope is of no use as a glass to spy things with on the surface 
of the Earth. 

How to Make a Cheap Telescope. — Lenses are absurdly 
cheap. If you live in a large city you will find lens grinders 
who will sell you the kind of lenses you need for either kind of 
telescope for a dollar or so. 

Telescope No. 1. — This telescope is fashioned after an opera 
glass, that is, it has a concave lens for an eyepiece. 




-5JST- 



j:l 



% 



*\<v 



ILL. 



^HEAVY PASTE BOARD THIN CARDBOARD 

Fig. 153. — Pasteboard Mounting of Lens. 

Get two pasteboard tubes of the kind described for the 
pinhole telescope; the bore, or hole, of the first tube should be 
1% inches in diameter and it should be 2 inches long. Have 
the second tube a little smaller than 1% inches in diameter on 
the outside so that it will slide easily into the larger tube and 
yet not leak light, and have this tube 1% inches long. 



THE SPYGLASS OR TELESCOPE 



141 



GLUE HERE 



*— * 



Paint the inside of both tubes with black paint to keep the 
walls of the tube from reflecting any stray rays of light which 
may strike them. The outside of both tubes can be covered 
with bookbinders' cloth to give them a neat appearance. 

The next step is to mount the lenses. 
The larger lens for the object glass is a 
double convex lens 1% inches in diameter 
and having a 12-inch focal length, or focus, 
as it is called for short. A lens of this 
kind can be bought for 25 or 30 cents. 
The smaller lens for the eyepiece is a 
double concave lens 1 inch in diameter and 
having a focus of 6 inches. This lens can 
be had for about 40 cents. 

Cut a strip of thin, tough cardboard % inch wide and 6 
inches long; on this strip glue a strip of heavy pasteboard % 
inch wide and 5% inches long, and have one end of both pieces 
even, as shown in Fig. 153. Set a flatiron on the pieces and let 
them dry. When dry make a groove down the middle of the 



Fig. 154. — Paste- 
bo akd Lens Mount- 
ing. 



OUTSIDE PASTEBOARD ^ t ^ m 

TUBE MOUNTING INSIDE 

TUBE 




Fig. 155. — Opera Glass Telescope. Cross Section. 



heavy pasteboard by slicing out a very thin strip with the point 
of a sharp knife, being careful not to cut through the thin card- 
board. Now bend the strips around the lens with the lens in 
the groove, glue over the thin end as shown in Fig. 154, and slip 



142 THE BOOK OF THE STARS 

a rubber band or tie a string around it to hold it in position 
until it has dried. 

The small concave lens, or eyepiece, is mounted in the same 
way, but since the lens is only 1 inch in diameter, cut the strip 
of cardboard % inch wide and 4*4 inches long and the strip of 
thick pasteboard % inch wide and 3!/2 inches long; this done 
glue them together, cut the groove and mount the lens as be- 
fore. 

The next and last thing is to smear glue on the cardboard 
mounts and push the convex lens in the end of the large tube 
and the concave lens in the end of the small tube. Now slide 



i / / r i / / // / J J / 






WMW/A "" '- 



Fig. 156. — Telescope. Cross Section View. 

the tubes together and you will have as good a telescope as the 
boy who invented it. It is shown in cross section in Fig. 155. 

You should, however, make two caps, one for each end of 
the telescope to cover the lenses when not in use. This little 
telescope is very handy to carry along on your scouting trips, as 
it takes up so little room, being only 2 inches long when closed 
up. 

Telescope No. 2. — This telescope is very much better than 
the one just described for seeing the stars as it magnifies about 
4 times. 

It is made exactly like the first one except that the larger 
tube is 9 inches long and the smaller tube is 5 inches long. In 
this telescope both lenses are double convex, the large one, or 
object glass, having a diameter of 1% inches and a focal length 
of 12 inches, while the smaller lens, or eyepiece, has a diameter 
of 1 inch and a focal length of 3 inches. It is shown in cross 



THE SPYGLASS OR TELESCOPE 



143 



section in Fig. 156. A spyglass usually has four or five plano- 
convex lenses in it and these not only magnify the image but 
they also erect it so that you see the object as it really is. 

While the homemade telescopes which I have described will 
not magnify as highly as a cheap telescope which you can buy, 
yet you ought to make one, for it will let you into the secret of 
combining lenses, and this is as interesting as seeing the stars. 
By all means make your first telescope and then if you want a 
better one buy it and get one as large as you can afford. 




A 8 

Fig. 157. — Magnifying Power of Telescope. 



To Find the Power of a Telescope. — In the last chapter, I 
explained what the focal length of a convex lens is, see Fig. 146, 
and how to measure it. To repeat, it is the distance in inches 
between the center of a lens and the point where the rays come 
together. 

You can find exactly what the magnifying power of your 
telescope is, when both lenses are convex, by dividing the focal 
length of the object glass by the focal length of the eyepiece, 
or lens. 

For instance, suppose the focal length of the convex object 
glass of your telescope is 12 inches and the focal length of the 
convex eye lens is 3 inches, then 3/12 and the quotient 4 is the 

4 
magnifying power in times or diameters of your telescope. 

To find the focal length of a concave lens is a little harder, 



144 THE BOOK OF THE STARS 

but Garrett P. Serviss tells us in his good little book on As- 
tronomy with an Opera Glass of an easy way to judge the 
magnifying power of an opera glass and it is just the same 
for a telescope. Look at a brick wall through one of the tubes 
with one eye while the other naked eye sees the wall direct. 

Now notice how many bricks which the naked eye can see, 
are needed to equal the thickness of one brick as seen through 
the glass. The number of bricks seen with the naked eye repre- 
sents the magnifying power of the glass. Fig. 157 shows how 
the bricks are compared. 

The Stars Seen Through a Spyglass. — The Moon. — When 
Galileo lived the people believed that the Moon was a ball as 
smooth and bright as a glass marble and they also thought that 
the dark spots on its surface were the continents of our Earth 
reflected by it. 

So the first thing Galileo did when he got his telescope was 
to turn it on the Moon, for he wanted to know about these dark 
spots, and you can imagine his surprise and delight to find that 
they were really great mountains and extinct volcanoes. 

You cannot do better than to point your little homemade 
telescope at the Moon, stop, look and rediscover the mountains 
on it and be as surprised and delighted as Galileo was, three 
hundred years ago. To see the mountains at their best do not 
wait until the Moon is full, for the sunlight then shines directly 
on top of the mountains and there are no shadows to help the 
eye to gauge breadths and heights. 

The best time to see the mountains is when the Moon is in 
its first or its last quarter, for then they are well brought out by 
the bright sunlight shining on them from the side and the black 
shadows which they cast on the other side. 

The great smooth stretches seen on the Moon are called seas. 
It may be that in the long ago they were really seas, but it is 
more likely that Galileo and the early observers whose telescopes 
were little better than yours thought they were seas. Then 
there are huge cracks or gorges on the surface of the Moon, 
which start from some of the craters and run for hundreds of 



THE SPYGLASS OR TELESCOPE 



145 



miles in every direction. A number of these gorges start from a 
volcano named Tycho (pronounced Ti'-co) and make the Moon 
look as if it is cracked; and it is likely that when the Moon 
cooled down from its melted state after having been shot off 
from the Earth it did crack in many places. Fig. 158, which is 




Fig. 158. — Full View of Moon. 



a good telescopic view of the Moon, shows some of these great 
cracks radiating from Tycho. 

To show on a small scale how the Moon cracked on cooling 
down Nysmith filled a glass globe with cold water and then 
sealing the globe he plunged it into hot water. The slow ex- 
pansion of the cold water by the hot water caused the globe to 
crack as shown in Fig. 159, and by comparing the pictures it 
will be seen that the cracks on the Moon and in the glass globe 
are very much alike. 



146 THE BOOK OF THE STARS 

There is a mountain called Aristarchus * (pronounced Ar-is- 
tar'-cus) which is believed to be formed of pure metal because it 
shines brighter than any other mountain on the Moon. Its posi- 
tion is shown on the map, Fig. 160. 

The instant you look through your glass at the Moon the 
man which shows so plainly to the naked eye vanishes like a 




Fig. 159. — Glass Globe Cracked. 

coin in a magician's fingers and instead you will see a new 
world covered with plains and mountains. 

But if you will look at the Moon when it is nine or more 
days old, you will see with the aid of your glass and a little im- 
agination the Moon girl, as shown in Fig. 161. You should 
have no trouble in finding her, for the Apennines form her 

1 Aristarchus was a Greek who lived 200 years before Christ. He 
taught that the earth was round. 



NORTH 




SOUTH 

Fig. 160. — Map of the Moon. 




Fig. 161.— The Moon Girl. 
147 



148 THE BOOK OF THE STARS 

crown while Tycho shines upon her breast like a great yellow 
diamond. 

There is another crater mountain which you should by all 
means know and that is Copernicus 1 (pronounced Ko-per'-ni- 
kus). Look through your glass at the southeastern end of the 
Apennines and you will see a crater that is larger in diameter 
than Tycho, though it is not so deep. Tycho, Copernicus and 
the Apennines will serve you well as landmarks if you follow up 
the explorations of the Moon which you have so well begun. 

The Sun. — You can see the spots on the Sun quite well with 
your glass, and sunspots are always interesting. 

Do not try to look at the Sun through your glass without 
covering the eyepiece either with a thickly smoked or dark- 
colored glass. You must also use smoked or colored glasses 
over your eyepiece when you are looking at an eclipse of the 
Sun. 

This year, 1915, is one of the best years to see sunspots, 
for more can now be seen than at any other time since 1904, 
or which can again be seen until 1926. 

The Planets. — After you have seen the mountains on the 
Moon and the spots on the Sun you should next turn your glass 
on the planets. 

While you will probably say that the planets loom up very 
small — the largest, Jupiter, appearing about the size of the 
head of a large pin — yet they are wonderful to look at even 
through the smallest telescope. 

Mercury. — This is a planet not easy to see even with the aid 
of a glass so if you see it you can think that you are lucky or 
skillful or perhaps a little of both. 

Venus. — Venus can be seen very much better with your small 
glass than Mercury, but you will only be able to see it as a little 
disk and not as a crescent for your glass is of too low a magnify- 

1 Copernicus — Polish astronomer. Born 1473. Before his time it was 
believed that the Sun, Moon and stars revolved round the Earth. 
Copernicus showed that the Earth was a planet and, with the others, 
that it revolved round the Sun. 



THE SPYGLASS OR TELESCOPE 149 

ing power. It is a brilliant object though even through the 
smallest glass. 

Mars. — While you cannot see the canals of Mars with your 
glass you can see it as a bright disk of light and this is well 
worth while. Mars is believed to be peopled and the thought 
that it may be makes it a mighty interesting object to look at. 
Look at it through your glass and think it over. 

Jupiter. — On account of his great size you will be able to see 
Jupiter better than any of the other planets. His disk will show 
clear and distinct and if you have good eyesight and your glass 
is fairly good you will be able to see one and perhaps two of 
his nine moons which will appear as little points of light close to 
the planet. 

Saturn. — The rings of Saturn cannot be seen with a glass 
magnifying less than four times. His rings are at this writing 
(1915) in the best position to be seen as the flat side of the 
rings is toward us now. In 1921 the edge of his rings will be in 
a line with the Earth and then it will be very hard to see them 
even with a much larger telescope. 

Uranus. — Although Uranus is so very far away, it can be 
seen with your glass, though you may not be able to see it as a 
disk of light. 

You can tell when you have found Uranus by watching it 
for a few nights. If it changes its position among the stars 
around it you will know you are looking at Uranus. 

Neptune. — Neptune is farther away than Uranus and your 
glass will show it as a mere point of light. Like Uranus you 
will know it if you see it, by its motion among the stars. 

The Stars. — After you have looked at the Sun, Moon, and 
planets to your hearts' content turn your glass on the Big Dip- 
per and you will see about ten times as many stars as you can 
see with the naked eye. 

The Big Dipper is full of starry surprises as you will find to 
your pleasure on looking at it with your glass : for instance, in- 
stead of the handle being formed of three stars, it blazes with 
dozens of them. 



150 THE BOOK OF THE STARS 

Take a look at Alcor, which is the middle star in the handle 
of the Dipper. Yon may remember I told you in the first chap- 
ter that it had a little companion, Mizar, which only sharp eyes 
can see. Now look at Alcor through your glass and you will see 
that it and Mizar are quite widely separated. 

The North Star is also a double star as these twin stars are 
called. Just as Mizar is a good test for the naked eye so the 
twin of the North Star is a good object on which you can try 
out the seeing power of your glass. 

Another double star which some boys can separate with their 
keen naked eyes is Epsilon, named after one of the Greek letters 
(See Appendix C). This star together with Vega, a very bright 
and beautiful blue star of the first magnitude, and Zeta, an- 
other Greek letter star, form a triangle, which is the constella- 
tion of Lyra. 

Whether or not you can separate Epsilon into two stars with 
the naked eye, you will see them stand out separate and distinct 
through your glass. If you had a more powerful glass you 
would see that each of the stars of Epsilon has a faint compan- 
ion star, so that it is really a quadruple star, that is, there are 
four stars right together. 

Then there is the Milky Way, always a wonderful sight to 
the naked eye, but still more wonderful when viewed through a 
glass however small ; there are the stars of the Pleiades of which 
the eye sees not more than six or seven without help, but which 
bursts forth like a skyrocket into a cluster of many-colored 
lights when seen through a glass; these are only a few of the 
hundreds of other things which you can see in the sky with 
the help of your little telescope. 



CHAPTER X 

THE TIME O' DAY 

What Time Is It? — This is a question everybody is always 
asking everybody else. 

Did yon ever stop to think what a cnrions thing time is? 
K"o one knows when it began nor can anyone tell when it will 
end, yet we measure off a little bit from that which has gone 
or from that which is yet to come, so that we may know when 
to eat, to start to work, or to quit, and when to go to bed or to 
get up. 

We know that, roughly, a year is the time it takes the four 
seasons to come and go, and that this is done when the Earth 
travels once round the Sun ; that the month is based on the time 
it takes the Moon to travel once round the Earth ; that the week 
has nothing to do with the Sun, Earth, Moon or Stars, but is a 
pure invention, and, finally, that the day is the time it takes 
the Earth to turn once round on its axis. 

But when we want to know what time it is we mean, of 
course, what " the hour, the minute and, sometimes, even the 
second of the day is, and these are the small measured parts of 
time we want to find out about. 

The time it takes the Earth to make one complete turn on 
its axis is divided naturally into two parts, more or less equal, 
depending on where we live, and these parts are daytime and 
nighttime. 

This general division of time, marked by alternate daylight 
and darkness, may have served every need of the cave man at 
first, but just as he came to have sense enough to crawl into 
his cave to get out of the rain so the blazing Sun must finally 

151 



152 THE BOOK OF THE STARS 

have driven into his awakening brain its use to him as a means 
of marking time. 

As his savage mind grew less animal and more human, ideas 
were formed in it either by instinct or by the first vague glim- 
merings of reason and he began to think. He saw that when 
the light of the Sun fell on the trees and the rocks, long, strange, 
black marks, which we call shadows, were cast by them, and he 
must have noticed that the shadows swung round the trees 
and rocks in the opposite direction to the way the Sun was 
traveling. 

To mark off with his eye and place a stone at a point some- 
where near the middle of the shadow cast by the rising Sun and 
that cast by the setting Sun, and which would mean that the 
day was half done was the next great step. 

These things were, quite likely, the first feeble efforts of the 
human race to measure time, and out of which the sundial came, 
as well as the crude beginnings on which the science of astron- 
omy is based. 

Solar Time, or Time by the Sun. — To make a sundial 
which would give correct Sun time was so hard a problem that 
men had to think about it for a million years before they could 
solve it and the chances are that then it was invented by a boy. 
You will find directions for making a simple sundial in Chap- 
ter III. 

Now let's find out how we can know when a day begins and 
when it ends. On first thought this would seem to be an easy 
thing to do and it is if we are not particular about being exact. 
You will remember that a day is measured by the time it takes 
the Earth to turn once round on its axis and what we want to 
know, now, is how to tell when the Earth has made one complete 
turn, no more and no less. 

We can tell this, you may say, by a clock or a watch, but 
the best of clocks and watches are always a little fast or a little 
slow, and time to-day is measured by the fraction of a second. 
So we get the apparent time from the Sun, change it into mean 
time and set our clocks and watches by it. 



THE TIME O' DAY 



153 



There are several ways by which we can obtain Sun time, but 
all of them are based on the same principle. The way that was 
used by people who first began to think about these things, and 
it is also a good way for you to try, is like this: 

First you must have a good horizon, that is, you must be able 

WHEN SUN CROSSES 
THIS LINE IT IS NOON 

O 




Fig. 162. — Diagram Showing How to Find Solar Noon. 



to see the Sun rise and set without any mountains or other 
things in the way. 

When you begin your observations for getting solar time note 
exactly where the Sun rises and where it sets on the horizon. 
You can easily do this by using hills, houses and trees for 
marking the places. Now with your eye draw a line between 
these two points. 

Notice also where you are standing and let your line of 
sight meet the imaginary line which joins the places where the 
Sun rises and sets just as near the middle as you can, and all 
of which is clearly shown in Fig. 162. Now this line will run 



154 THE BOOK OF THE STARS 

due north and south and hence it is a meridian line which you 
are to use to observe the Sun. 

When the Sun reaches that point in the sky where it is 
directly over the middle of the imaginary line, joining the 
places where it rises and sets, it is exactly noon, Sun time. 

The next day observe the Sun in the same way and when 
it crosses the meridian line again the Earth will have turned 
round once and you will have a part of time measured off called 
a Sun or solar clay. 

But when the time is taken between two succeeding crossings 
of a meridian by the Sun it is not true time and a day so meas- 
ured is called by astronomers an apparent solar day, and when 
the Sun is on the meridian it is called apparent noon. 

Xow the word apparent means to seem, that is, something 
which seems to be true and yet is not true. An apparent solar 
day is then the length of a day measured by the Sun, and while 
we might suppose that the Sun at least would give the true 
length of a day this is not the case for the reason that the Earth 
does not travel in all parts of its orbit round the Sun at the 
same rate of speed, and, further, it is tilted on its axis ; together 
these things make the days as measured off by the Sun unequal 
and hence they are called apparent solar days. 

Meaji Solai* Time. — Apparent solar days which aie of un- 
equal length were all right as long as sundials* were the only 
timepieces, but when clocks and watches came into use days 
which were equal in length were needed and needed badly, for a 
clock couldn't be made which would keep Sun time. 

So astronomers who watched the stars by night lay awake 
during the day wondering how they could make the Earth travel 
round the Sun at the same speed every day in the year and just 
as though it was not tilted. At last they solved the problem. 

And how do you think they did it ? It was as easy as roll- 
ing off a log — when you know how. They simply imagined 
that the Earth traveled at a uniform speed and that it stood 
straight, as shown in Fig. 74. In other words they took the 
mean length, which is another way of saying the average length 



THE TIME O' DAY 155 

of all the apparent solar days which make up a year, and divided 
it up equally. Further, the men who got up this scheme said 
that every day should have not only the same length, but that it 
should have 24 hours, and of course you know that hours are 
divided into minutes and minutes into seconds. Mean solar 
time, then, is really imaginary Sun time and this is the time 
used everywhere and watches and clocks are set by it. 

Equation of Time. — To get the exact mean time each day 
you have to know just what the apparent solar time is, and then 
you have to know what the difference in time is between the ap- 
parent solar time and the mean time, that is how many minutes 
and seconds to add to or subtract from the solar time of each 
day to get the mean time. 

This difference of time is called the equation of time. A 
table prepared by Professor Todd of the Amherst College Ob- 
servatory is given in Appendix M and can be used for all ordi- 
nary purposes. 

Standard Time. — A meridian, as you know, is an imaginary 
line running due north and south and hence we can have a 
meridian whenever we want it and as many as we like. 

When the Sun crosses the meridian of those who are on it, 
it is noon to them, but to no one else, for the Sun has already 
crossed the meridian to the east of it and has yet to cross the 
one to the west of it. 

As an illustration it takes the Sun about three hours to cross 
the United States from the Atlantic to the Pacific coasts. When 
the Sun crosses the meridian which passes through New York 
City it is noon here and it is likewise noon when the Sun crosses 
the meridians which pass through St. Louis, Denver and San 
Francisco, and this is true of every other place and of every 
other hour of the day. This is the reason why every place had 
its own, or local time, before the year of 1883. 

Now as long as people traveled on foot, or by horse, they 
moved so slowly that local time did not worry them, but when 
railroads came into use there was all kinds of trouble for the 
traveler; if he was going west his watch was faster than the 



156 THE BOOK OF THE STARS 

local time of the towns he passed through and if he was going 
east his watch was always slower than the local time. If he 
wanted the right time he had to set his watch at every town 
he passed through; of course he couldn't very well do this and 
he was always in a stew. 

The railroad companies were just as much put to for it 
was next to impossible to make a timetable to fit the local time 
of each town and still keep up a running schedule; and the 
result was that the railroads finally got up a system of their 
own which they called railroad time. This was all well enough 
for everybody but the poor traveler, who, not knowing the dif- 
ference in time between local time and railroad time, nearly 
always found he was either an hour too early or — as it usually 
happened — a minute or two too late to catch his train. 

As new towns sprung up and railroads multiplied, things 
had come to such a pretty pass in 1883 that nobody but the 
astronomers knew what the real time was, and they wouldn't 
tell; then a new time scheme was tried out, and as it is still 
used we must conclude it is a fairly good one. It is called the 
zone, or belt system of standard time; the time used is called 
standard time because the towns and cities and railroads all 
use it and there is no confusion. 

To understand what standard time means we have to know 
first what a standard meridian is. A meridian, as we have said, 
is an imaginary line running due north and south anywhere 
we want it, but while a standard meridian is also a line run- 
ning due north and south it has a fixed position. 

The first fixed or prime meridian, as it is called, passes 
through Greenwich (pronounced Gren'-ij), which is a part of 
London, England. The reason this meridian was chosen by 
geographers to reckon distance east and west from is because 
the Eoyal Observatory at Greenwich is one of the oldest in the 
world and it was the first from which exact time was sent out. 

If a circle is divided into 360 degrees, as shown in Fig. 163, 
and it is also divided into 24 parts, each part will be a space 
equal to 15 degrees or 1 hour. Now geographers have divided 



THE TIME O' DAY 157 

the Earth into 24 equal parts by meridians separated by 15 
degrees, and each space, or belt, between them represents 1 hour, 
as shown in Fig. 164. These fixed meridians start at the first, 
or prime meridian, at Greenwich and all the other meridians 
are measured in degrees east or west of Greenwich as the case 
may be. 




163. — Circle Divided into 360 Degrees and 24 Hours. 



Starting west from the first, or prime meridian, which passes 
through Greenwich the time at the second standard meridian, 
which is called the 15th meridian because it is 15 degrees from 
the first meridian, will be one hour behind Greenwich time. 

At every standard meridian the mean solar time is used as 
the standard time and every place on it and halfway to the 
meridian or both sides uses it, and so local time and standard 
time are now one and the same thing. 



158 



THE BOOK OF THE STARS 



This makes it very convenient for the traveler, for instead 
of setting his watch at each station he does not need to set it 
until he has traveled 15 degrees east or west; which is about 
500 miles in our northern latitudes, and then he turns it exactly 
one hour ahead or one hour back, depending on the direction 
he is going. 



,60™ , 



!20™ 



30™ 
15™ 

GREENWICH 

ERO OR 

PRIME 
MERIDIAN 




Fig. 164. — The Earth Divided into 24 Standard Meridians. 



There are four standard time meridians running through the 
United States, as shown in the map in Fig. 165. The one run- 
ning through New York, Pennsylvania, New Jersey and Dela- 
ware is the 75th meridian, meaning of course that it is 75 de- 
grees west of the prime meridian which passes through Green- 
wich. Time on this meridian and halfway to the meridians 
on both sides of it is called Eastern Time. It is just five hours 
slower than Greenwich time. 

The next is the 90th meridian and this one passes through 







Fig. 165. — Standard Time Meridians in U. S. 
159 



160 THE BOOK OF THE STARS 

Wisconsin, Illinois, Missouri, Tennessee, Mississippi and Louis- 
iana. Time on and around this meridian is called Central 
Time. 

The one after this is the 105th meridian and passes through 
Montana, Wyoming, Colorado, New Mexico and Texas. Time 
on and around this meridian is called Mountain Time. The last 
of the four meridians, the 120th, passes through the States of 
Washington, Oregon and California and time on and around 
this one is called Pacific Time. It is three hours slower than 
Eastern time and 8 hours slower than Greenwich time. 

Although these meridians are just one hour apart the time 
is not changed on them nor exactly in the middle of a belt but 
at some well-known town or city between two of the meridians, 
as you will see by looking at the map, Fig. 165. Fig. 166 shows 
the standard time at different cities around the world north of 
the equator. 

Star or Sidereal Time. — Besides all the different kinds of 
time described above there is still another and a very important 
kind of time, and this is obtained by the stars. 

Just as Sun, or solar time is obtained by noting when the 
Sun crosses a meridian, so star, or sidereal time is obtained by 
observing when a star crosses a meridian. Now there is a dif- 
ference between the length of a day when formed by the Sun 
crossing the meridian twice in succession and when formed by 
a star crossing the meridian twice in succession. This difference 
in time, between a solar day and a sidereal day, as they are 
called, is nearly four minutes. 

But the point is this: an astronomer can obtain the time 
from watching a star cross the meridian much more accurately 
than he can from the Sun, because a star is a mere point of 
light, and it is easier for him to calculate the mean solar time 
from the transit of a star than it is for him to go to bed, and 
besides he would rather do it, too. 

How Time Is Distributed. — In this country the correct 
standard time is sent out by the United States Naval Observa- 
tory at Washington to all cities east of the Eocky Mountains, 



THE TIME O' DAY 



161 



by wire telegraph, and all over the Atlantic ocean and seaboard 
by wireless telegraph. 

When time is received over the wires from Washington it 
is distributed by local telegraph or by time balls to various jew- 

PRIME MERIDIAN THROUGH GREENWICH ENGLAND 
I Z C.CLOCK. 

NOON 




^O'CLOCK 
MIDNIGHT 

Fig. 166. — Standard Time at Different Cities. 

elry stores and to private citizens who always want to be set 
right. 

How an astronomer gets the correct time; how it is sent 
out over the wires and by wireless and how it is distributed to 



162 THE BOOK OF THE STARS 

the common people is a mighty interesting piece of business. 
Briefly it is like this: 

How Correct Time Is Obtained. — Every observatory has, 
besides its big telescopes, a transit instrument, a wonderfully 
accurate clock, and a clockwork device called a chronograph. 
The transit instrument is nothing more than a telescope with 
a thin piece of clear glass with a number of lines ruled on it 
with a diamond, about % i ncn apart, and this ruled glass is set 
between the eyepiece and the object glass, as shown in Fig. 
1G7. 

This telescope, or transit instrument — so called because it is 
used to observe the transit, or passage, of a star across a merid- 



3 — 



RULED GLASS 

Fig. 167. — Ruled Glass in Transit Instrument. 

ian — is set on an axis so that the telescope can be pointed' to 
any place on the meridian but it cannot be moved east or west. 

Sometime before a star is due to cross the meridian the 
astronomer sets his transit instrument so that the star will pass 
right across the line of sight of his telescope. 

The purpose of observing the transit, or passing of a star 
is to see how much his wonderfully accurate clock has lost or 
gained during the past 24 hours. So his clock is right at hand. 

The chronograph is another accurate clockwork which re- 
volves a cylinder about the size and shape of a phonograph 
cylinder, and around which is wrapped a sheet of white paper. 
This cylinder makes one revolution every minute. A fountain 
pen marks a spiral line on the paper when the cylinder is re- 
volving but at every second the pen is thrown out of position and 
this makes a notch in the line. 

After starting the chronograph the astronomer takes an elec- 
tric push button, which is connected with and controls the 
lever which holds the pen of the chronograph that makes the 



THE TIME O' DAY 163 

notches, and takes up his position with his eye at the end of 
the transit instrument. 

The instant he sees the star in the telescope he presses the 
button and this closes the electric circuit and makes a big notch 
in the line traced on the paper of the chronometer. 

From the position of the big notch — which he caused to be 
made on the line when the star crossed the meridian and the 
little notches made regularly every second — he can dope out 
just how much his clock is in error — that is, how much it is 
too fast or too slow. 

The next thing he does is to change this absolutely correct 
star time into mean solar time, when it is ready to be sent all 
over the United States east of the Eocky Mountains by tele- 
graph. The Pacific Coast folks get their correct time from a 
Government observatory at Mare Island in San Francisco Bay. 

How Time Is Sent by Telegraph. — The wires of the Wes- 
tern Union Telegraph Company run into the United States 
Naval Observatory at Washington, and for a few minutes each 
day all of this company's wires are controlled by the Govern- 
ment. 

About five minutes before 12 o'clock noon, standard time 
at Washington, each day the wires all over the country east of 
the Eockies are cleared and all business and other messages are 
cut off for the time signals. 

At five minutes of 12 sharp the United States Naval Obser- 
vatory begins to send the beats of every second of the wonder- 
fully accurate observatory clock, which are ticked out on tele- 
graph sounders in all the cities and towns. 

But no, not every beat, for the 29th second of each minute, 
the last 5 seconds of each of the first 4 minutes, and then the 
last 10 seconds of the last minute are not sent. The first click 
of the sounder after the 10 seconds' rest is the noon signal, and 
all local clocks are set by it. 

In many cities the telegraph company has special wires run- 
ning to various jewelry and other stores and these subscribers 
get the correct time direct by telegraph from the Naval Ob- 



1164 



THE BOOK OF THE STARS 



servatory for their sounders are connected in the regular line 
circuit. 

The Time Ball. — The Bureau of Navigation got up what is 
known as the time ball for the benefit of sailing masters in par- 
ticular and the townsfolk in general. 

In New York and other cities along the seacoasts and lake 
ports a great ball, weighing in the neighborhood of 100 pounds, 




Fig. 168.— The Time Ball. 

having a diameter of over 3 feet and with a hole in its center, is 
slipped over a pole or flagstaff some 20 feet in height, which is 
mounted atop of some high building where it can be seen to the 
best advantage. 

The ball is held in position at the top of the pole by an 



THE TIME O' DAY 



165 



electro-mechanical trigger, which is placed directly in the elec- 
tric telegraph circuit that runs into the Naval Observatory at 
Washington. When the time signals are being sent out from the 
observatory and the telegraph key is closed at exactly noon the 
trigger which holds the ball 
in place is released by the 
current and the ball drops. 
Fig. 168 shows a time-ball 
atop of the old Western 
Union Building in New York. 

How Time is Sent by 
W i r e 1 e s s. — At Arlington, 
Va., just across the Potomac 
River from Washington, is 
one of the most powerful 
wireless stations in the world, 
having a sending range of at 
least 3,000 miles. 

Every day at noon time 
signals like those sent over 
the wires on land are sent out 

so that every navigation officer and sailing master whose ships 
are fitted with wireless apparatus can get the correct time. 

All over the Atlantic seaboard boys, as well as jewelers (see 
Fig. 169), have wireless receiving sets and they receive the cor- 
rect time every day by wireless free of charge. No license is 
required to receive wireless signals, the cost of the apparatus is 
little and the experience immense. Are you in on it ? 




Fig. 



169. — Receiving Time 
nals by Wireless. 



Sio- 



CHAPTEK XI 

THE STARS OF THE ZODIAC 

Zodiac! — It sounds to the untrained ear like the password 
of a bomb-thrower or a first cousin to a dish of Hungarian gou- 
lash. 

It is enough, albeit, to scare even a Scout away from the 
stars, but be not afraid, for it can't hurt you and you can't 
eat it. 

On the other hand, if you are on speaking terms with the 
zodiac (pronounced zo'-di-ak), it will help you to find the plan- 
ets and at the same time you will add enough new constellations 
to those you already know to give you a high passing mark for 
a merit badge in the Boy Scouts if you want one. Besides, the 
signs and constellations of the zodiac will aid you to use the 
almanac and help you in many other ways. 

You have often noticed that the Sun seems to travel through 
the sky over a path or belt that is always the same from east to 
west; you must have noticed, too, that the path of the Moon is 
almost the same as that of the Sun, but you may or may not 
remember that the planets also travel over the same path as the 
Sun and Moon. 

It is just as though the Sun, Moon and planets were all 
fastened on a great endless belt in the sky which turns round 
the Earth nearly in a line with its equator, though tilted at a 
slight angle to it, and this line is called the ecliptic. The way 
the ancients thought it was and the way it really looks to us is 
shown in Eig. 170. 

The ancients called this apparent path of the Sun, Moon 
and planets with the stars for a background the zodiac, so it is 
not such a horrible specimen after all. 

166 



THE STARS OF THE ZODIAC 



167 



We know, of course, that the Sun is the center of our solar 
system and that the planets, including the Earth and Moon, are 
at various distances from the Sun and that each moves in a 




^?" 



Fig. 170. — The Zodiac as Invented by the Ancients. 



path, or orbit, of its own, so that what we call the zodiac is 
really a belt a little wider than the path of the Sun caused by 
the Earth traveling round it. 



\ C . A !^*J-----* / 




'•--*T JUP 'TER """zOOl^... 



Sco *pio 



I *- ^' 

Fig. 171. — The Zodiac as We Know It Today. 



Suppose we draw a little circle and call it the Sun, as shown 
in Fig. 171, and draw an ellipse around it and call it the Earth's 
orbit, putting on another little circle for the Earth; now sup- 



168 THE BOOK OF THE STARS 

pose we draw a much larger ellipse round the one representing 
the Earth's orbit, divide it into 12 parts and put a constellation 
in each part. 

Knowing now that the Sun, Moon and planets are very near 
the Earth when compared with the fixed stars it must be plain 
that these bodies when seen from the Earth, which is always 
changing its position in its travels round the Sun, would appear 
to move in and across the constellations. 

Take a look at Jupiter some night when he is moving across 
any of the constellations and he will seem to be a part of it; 
this is the reason we speak of the Sun or a planet, as being in a 
certain constellation at a given time. 

The stars forming the background of the Moon and the 
planets can always be seen, for we are then looking at them 
from the dark side of the Earth, but they cannot be seen when 
they form the background of the Sun, for the stars are on the 
other side of him when he gets between us and them and he 
shines in our eyes. 

These constellations through which the Sun, Moon and plan- 
ets seem to pass, or as the almanacs say are in, lie in a belt 
formed by the path of the Sun and neither the Moon nor the 
planets ever get farther from the path of the Sun than 8 de- 
grees on either side of him and this belt is called the zodiac. 

The belt, or zodiac, is divided into 12 equal parts, or spaces, 
which were called signs by the ancients and they are still called 
signs. This makes the length of each sign, or space, 30 degrees, 
and hence the 12 signs, which are called the Signs of the Zodiac, 
equal 360 degrees or a complete circle. (See Chapter X, The 
Time o' Day.) 

The Signs of the Zodiac have the following constellations in 
them in this order: Aries, the Ram; Taurus, the Bull; Gem- 
ini, the Twins ; Cancer, the Crab ; Leo, the Lion ; Virgo, the Vir- 
gin; Libra, the Balance; Scorpio, the Scorpion; Sagittarius, the 
Archer; Capricornus, the Goat; Aquarius, the Water Bearer, 
and Pisces, the Fishes. It is in one of these constellations that 
the Sun, Moon and planets are always to be found. 



THE STARS OF THE ZODIAC 



169 



A good way to find any one of the constellations is by know- 
ing the time when it will be on your meridian, that is the line 
due north and south which you are on, during a given month. 
Any constellation of the zodiac will be on your meridian at 
9 o'clock P. M., during the month given opposite its name in 
the following table: 



Astronomical 

Names 


How Pronounced 


Common Names 


Time Constellation will 
Appear on Your 
Meridian at 9 p.m. 


Aries 


A'-ri-es 

Tau'-rus 

Gem'-i-ni 

Can'-cer 

Le'-o 

Vir'-go 

Li'-bra 

Scor'-pi-o 

Sag'-it-ta'-ri-us 

Cap'-ri-cor'-nus 

A-qua'-ri-us. . . 

Pis'-ces 


The Ram 
The Bull 
The Twins 
The Crab 
The Lion 
The Virgin 
The Balance 
The Scorpion 
The Archer 
The Goat 
The Water- 
Bearer 
The Fishes 


December 


Taurus 

Gemini 

Cancer 

Leo 


January 

February 

March 

April 

May 

June 


Virgo 

Libra 


Scorpio 

Sagittarius . . . 
Capricornus. . . 
Aquarius 

Pisces 


July 
August 
September 
October 

November 



To find any constellation during any other month than that 
given in the last column above subtract two hours for each fol- 
lowing month. Suppose you want to find Aries, the Earn, in 
January instead of December, look for it on your meridian at 
7 P. M. ; in February look for it at 5 P. M., and so on. 

You will of course come to a month where the constellation 
will run into daylight and then you won't be able to see it again 
until the Earth has traveled round the Sun to a point where the 
Earth is again between the Sun and the constellation. 

The constellations of the zodiac are shown in Fig. 172; in 
this figure they are marked on a strip which is divided into 12 
signs, or parts, and in these the chief stars of each of the con- 
stellations are placed. 

If you look southward at the sky some night for any particu- 
lar constellation you need not expect the stars which form it 



170 



THE BOOK OF THE STARS 



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to stand out separate and distinct, 
as shown in Figs. 172 and 174; 
if yon do yon will be sadly disap- 
pointed, for many of the constel- 
lations of the zodiac are very poor 
specimens compared with the Big 
Dipper, or Orion, or Pegasns. 

Nor are the constellations of 
the zodiac measured off in the sky 
by any such even lines as are 
shown in Figs. 172 and 174. On 
the contrary some of the stars are 
very scattered and stretch over 
part of two signs of the zodiac, 
while others do not take up nearly 
all the space allowed them, but all 
12 are there — count 'em. 

The heavy black line drawn 
lengthwise through the middle of 
the strip in Fig. 172 represents 
the line of the ecliptic which is 
•the yearly path the Sun seems to 
take. The planets also take the 
same course, though they may be 
on one side or the other of the 
Sun's path — the black line of the 
drawing — by 8 degrees, thus mak- 
ing the zodiac 16 degrees wide; 
hence, the lighter parallel lines on 
either side of the black line, or 
path of the Sun, is the farthest 
away that the planets ever get. 

If you were to cut the strip of 
paper, Fig. 172, out of the book 
and paste the ends together, you 
would have a band, or circle repre- 



THE STARS OF THE ZODIAC 



171 



sen ting the zodiac more nearly as it is; but instead of cutting 
the book yon had better draw the signs and constellations on a 
strip of cardboard 2 inches wide and 24 inches long and glue 
the ends together, as shown in Fig. 173; you will now have a 
zodiac with which you can do a little experimenting. 




Fig. 173. — Cardboard Zodiac. 



Place a candlelight in the center of the cardboard ring and 
suspend a marble from a thread, by means of a drop of sealing 
wax, and let the marble hang between the light and the card- 
board zodiac. Now on whatever space, or sign on the band the 
shadow of the marble falls, the candle light, which represents 
the Sun, is said to be in the constellation in a line with the 
shadow on the opposite side. 

In the almanacs our year begins with January and as the 
Sun is then in Aquarius this constellation is represented by a 



172 



THE BOOK OF THE STARS 



picture of Aquarius, the Water Bearer ; but in marking out the 
constellations of the zodiac on a flat strip of paper we begin 
with Aries, which is March, on our calendar and read them from 
right to left. 

The reason for this is because the Earth travels round the 




Fig. 174. — Constellations of Zodiac in Circle. 



Sun from left to right when we face the north and this makes 
the Sun appear to move through the constellations of the zodiac 
from right to left. 

This makes all the months follow each other in the proper 
order when the strip of paper is glued together, as shown in 



THE STARS OF THE ZODIAC 173 

"Fig. 173, or when the constellations are arranged in a circle, as 
shown in Fig. 174. 

This latter diagram shows plainly that when the Earth is 
at that part of its orbit marked A and we are on that side of 
the Earth which is toward the Sun the constellation of Taurus 
is back of the Sun, and of course we cannot see Taurus for the 
Sun, which is shining in our eyes. 

Still Taurus is the background of the Sun just the same, 
and so when the almanac says the Sun is in Taurus you will 
know that the Sun is directly between the Earth and Taurus. 

The same thing is true of all the planets. Take Mars, for 
example; whenever Mars is in that part of its orbit so that we 
can see it at night, as shown at B, Fig. 172, we also see the 
constellation back of it — in this case it is Libra, the Balance — 
and since a planet and a fixed star look exactly alike to the 
naked eye it is easy to think of Mars as being in that constella- 
tion; and it is the same with all the other planets. 

The Constellations of the Zodiac. — The Constellations of 
the Zodiac and the Signs of the Zodiac are two very different 
things. Long ago, when the zodiac was invented, the constella- 
tion of Aries, the Earn, was in the first of the 12 spaces and he 
and the sign of this space were of course at that time the same. 

Owing to a peculiar motion of the Earth, called precession, 
the constellations of the zodiac have moved forward during the 
last 2,000 years and the space, or sign, as it is called, where Aries 
used to be is now occupied by the Pisces, the Fishes, but the sign 
of this space is the same now as it was then. 




Aquarius, the Water Man. — A constellation of autumn : 
Aquarius is always pictured in the almanacs as pouring water 
from a pitcher. 

All the stars of this constellation are faint and scattered 



174 



THE BOOK OF THE STARS 



and none of them are in a line with, the ecliptic. Aquarius got 
his name from the Bomans, who called him the Waterman 
because when the Sun enters the constellation in January there 
are usually heavy rains in Italy and in the long ago people 
thought the stars had a lot to do with the weather, and every- 
thing else on Earth, for that matter. 




Fig. 175. — Constellations of Aries the Ram. 



Pisces, the Fishes. — This constellation is now in that part 
of the zodiac whose sign is °p (Aries). It is not an interesting 
constellation to look at with the naked eye, for its stars are 
faint and they stream out in two lines over nearly two signs 
of the zodiac. 

But Pisces is none the less a very important constellation 
because it is at one of the points where the line of the equator 
crosses the line of the ecliptic. 

When the Sun crosses the point where the equator and the 
ecliptic meet the days and nights are then equal at all places 
on the Earth, and hence we call this time of the year, which is 
about the twenty-first of March, the equinox, which means 



THE STARS OF THE ZODIAC 



175 



equal days ; or the vernal equinox, which means equal spring days. 
Aries, the Ram. — This constellation used to be in that part 




of the zodiac whose sign is °p (Aries) but is now in that part 
whose sign is # (Taurus). 

The position of Aries in the sky is shown in Fig. 175 and 
you can easily find him by drawing a line from the North Star 




to Gamma in Pegasus and another line at right angles to the 
first line until you come to two bright stars quite close to- 
gether and these are the chief stars of the constellation of the 
Earn. 

Taurus, the Bull.— This constellation is now in the sign n 
( Gemini) , of the zodiac. In Chapter II you will find direc- 
tions for locating Taurus. You will remember that the red 




star Aldebaran forms the right eye of the Bull. The little 
group of stars called the Hyades is the Bull's face and the 
Pleiades are in his shoulder. 

Gemini, the Twins. — It is easy to see why the ancients 
called this constellation of the zodiac the Twins, for its two 
chief stars, Castor and Pollux, are very close together and while 
of different colors they are of about the same brightness. 



176 THE BOOK OF THE STARS 

These two stars are the heads of the Twins and four other 
stars are their feet and these stand forever on the Milky Way. 
The Twins are easily found since they are next to Taurus, the 
Bull. 




Gemini is an important constellation, as the Sun reaches 
its most northern point in it in summer; this is called the sum- 
mer solstice, and takes place about June 21. When the Sun 
has reached this point it casts the shortest shadow at mid-day 
and it seems to stand still for a few days before it takes its 
downward course. The summer solstice is halfway between the 
two points of the equinox. 

Cancer, the Crab. — This is a small constellation of dull 
stars that is chiefly interesting because it was once the point of 
the summer solstice, but that was ages ago. 

The only thing about Cancer to attract attention is a hazy 
patch of light called the Manger. On each side of the Manger 




is a fairly bright star and this pair of stars is called the Ass's 
Colts; they will help you to find Cancer. 

The Manger has often been mistaken for a comet by those 
who lit upon it with the naked eye, but it is really a cluster of 
small stars. 

Leo, the Lion. — There are two separate groups of stars that 
make up this king of beasts. The first group takes the shape of 
a sickle and the other the form of a square. The sickle, which 
is formed of six bright stars, is Leo's head and shoulders, and 



THE STARS OF THE ZODIAC 



177 



the four stars of the square make up his hindquarters. 
Two lines, drawn from the Big Dipper across the sky until 
they touch the path of the Sun, or ecliptic, as shown in Fig. 
176, will meet the sickle and the square. 




The very bright star in the end of the handle of the sickle 
is Begulus, which means little king, and far to the other side 




Fig. 176. — Constellations op the Lion and Big Dipper. 



of the constellation right in the end of the Lion's tail is another 
bright star called Denebola. 

Virgo, the Virgin. — This constellation is of interest, be- 
cause the Sun again crosses the point where the equator and 
ecliptic meet, and the days and nights are again of the same 
length everywhere on the Earth, just as they were at the spring, 
or vernal equinox. 

But this time, when the Sun is in Virgo, it crosses the line 
of his journey south about September 21 and so this equinox 



178 



THE BOOK OF THE STARS 



is called the autumnal equinox, which, means equal autumn 
days. 

By drawing a line through the handle of the Big Dipper 
and producing it to Arcturus, and on until it reaches a big, 




bright, white star you will have reached Virgo, as shown in 
Fig. 177. This big, white, bright star is Spica, and it is 
the chief star in Virgo. 

The ancients always represented Virgo, the Virgin, with a 
sheaf of wheat in one hand and a sickle in the other. The 
Virgin and the harvest always went together in the minds of 
the ancients and this accounts for the pictures of Virgo in the 
almanacs of the present time. 

Libra, the Balance. — A small constellation named for the 
ancient Eoman pound weight. 

The constellation of Libra is not nearly as old as the others 
in the zodiac, in fact it is thought that there were only eleven 




constellations in the zodiac when they were first mapped out 
thousands of years ago, although there were twelve signs or 
spaces in the zodiac. Its position is shown in Fig. 178. 

Then in the days of the Roman Empire, about 300 years be- 
fore Christ, some genius clipped the claws of the Scorpion and 
made its stars into a pair of scales. This was a very clever 
idea, for the autumnal equinox then took place in this sign of 
the zodiac, and the stars in this sign were given the name of 
Libra, as the equal days and nights called to mind the balance. 



Fig. 177. — Constellations op Virgo the Virgin. 



REGULUSIN 
A ARCTURAS ^ThELION 

|\ IN BOOTES s^ 



ALPHA 
IN LIBRA* 



SPICAIN 
VIRGO 



Fig. 178. — Libra, Lion, Scorpio, Virgo. 
179 



180 THE BOOK OF THE STARS 

Scorpius, the Scorpion. — A summer constellation. If Libra 
takes up only a small part of one sign of the zodiac Scorpius 
makes up for it by nearly covering two signs. 

To the old astrologers, Scorpius was the "power of darkness" 
and the "accursed constellation/' and when they cast their horo- 




scopes they attributed to it "woe and discord, war and disease." 

The constellation of Scorpius is one of the very few which 
really looks its part. In the end of its curved tail there are two 
stars which are ready to sting if he ever strikes, but he has 
never struck yet. 

The heart of the Scorpion is a big, bright red star called 
' Ardour es, which means the rival of Mars, and when Mars is in 
the constellation of Scorpius it is hard to tell them apart. 

Antares will prove useful in finding the Scorpion as there are 
no other bright stars in that part of the sky. The position of 
Scorpius is shown in 178. 

Sagittarius, the Archer. — A summer constellation : It is 
made up of eight stars which can be seen with the naked eye 




and is always pictured in the almanacs as a centaur, or man- 
horse, shooting an arrow from a bow at the heart of the Scor- 
pion. 

Sagittarius is a fine constellation, right in the path of the 
Milky Way, and this makes it easy to find. There are several 
interesting things in this constellation and among them are the 
clusters of stars and nebulae. 



THE STARS OF THE ZODIAC 181 

Then there are seven stars in Sagittarius, which make a little 
dipper turned upside down, and because it is in the Milky Way 
it is called the milk dipper; when you once find it, you will never 




VEGA IN 
LYRA 



ALTAI R IN 
AQUILA 



CAPRICORNUS 



Fig. 179. — Lyra, Aquila, Capricornus. 

be able to see Sagittarius again without seeing the milk 
dipper. 

The winter solstice, that is, when the Sun reaches its most 
southern point, lies halfway between the constellations of Scor- 
pius and Sagittarius and also between the two stream lines of 
the Milky Way. 

When the Sun reaches this point, which is the 20th of De- 
cember, the noonday shadows are the longest and the Sun seems 
to again stand still until Christmas, when he will begin to move 
north once more. 

Capricornus, the Sea-Goat. — A constellation of autumn: 
On the same plan that the ancients made Sagittarius a man- 
horse, so they made Capricornus a goat-fish. 

Though Capricornus is a small and poor constellation when 
viewed with the naked eye, the early astrologers thought more 



182 THE BOOK OF THE STARS 

of him than all the other constellations of the zodiac put to- 
gether. 

While the stars of Capricornus do not look anything like a 
sea-goat, he can be easily found by drawing a line from Vega in 




Lyra to Altair in Aquila and produce it until you come to the 
zodiac as shown in Fig. 179. 

The two brightest stars of Capricornus are in his head. 
One of these stars is a naked eye double, but to many people it 
will seem merely a single star. As a matter of fact it is a fine 
sight test, for it takes a pair of mighty good eyes to separate 
them. Another bright star of the sea-goat is in his fishlike tail. 

We have journeyed clear around the great circle which the 
Sun travels every year, and we are back again to Aquarius, the 
constellation we started from, having covered all the constella- 
tions of the zodiac. 

The Signs of the Zodiac. — Where the signs of the zodiac 
are used in almanacs they do not mean the constellations of the 
same name at all, but the spaces or parts of the great circle 
which form the zodiac. 

Two thousand years ago the constellations and the signs of 
the same name were in the same spaces or parts of the zodiac, 
but the constellations have shifted over one space to the east 
since that time, while the signs which used to represent them are 
still in the same spaces, and this has made a good deal of con- 
fusion. 

It's a pretty skillet of fish, this mixing of the signs and con- 
stellations of the zodiac, but you will get used to it just as easily 
as you get used to carrying water when in camp or washing 
dishes. 

How to Read the Almanac.— If you were asked to find the 



THE STARS OF THE ZODIAC 183 

date of any day of any month of the year you would simply look 
at a calendar and find it in a jiffy. 

Now, long before calendars came into general use the almanac 
was freely consulted, not only for learning days and dates, but 
for much more useful information, such as finding the dates of 
eclipses, the beginning of seasons, the rising and setting of the 
Sun, Moon and planets and the conjunctions and oppositions of 
these bodies, planting potatoes and the year the father of your 
country was born. 

To read an almanac easily you should learn the following 
signs: 

O The Sun $ Mercury 

O Full Moon $ Venus 

d Last Quarter © The Earth 

# New Moon $ Mars 

D First Quarter 

21 Jupiter 6 Conjunction 

^ Saturn 8 Opposition 

5 Uranus 

W Neptune 

Conjunction — When this sign is used it means that two 
planets, or the Sun and a planet, or the Moon and a planet, are 
on the same side of the Earth. 

Opposition. — When this sign is used it means that two 
planets, or the Moon and a planet, are on the side of the Earth 
opposite to the Sun. 

To see how these signs work out suppose you look up the 
month of January, 1915, in an almanac. 

The first line, besides showing that it is the first day of 
the year, the first day of the month and that it is Friday, also 
shows that the O (Moon) is full. It further gives the time 
the O (Sun) rises and sets, the length of the days in hours 
and minutes, the O (Moon's) age in days, and when it rises 
and sets. 



184 THE BOOK OF THE STARS 

Then on the same line the following signs are given : 6 tf 6 
and this means that a conjunction of Mercury and Mars will 
take place on this date; that is, that they will be nearer to each 
other from our line of sight than at any other time for a long 
while. 

On the next line, which is the 2nd of January, the following 
signs are given: $ greatest brilliancy; © in perihelion 
6 W C ; the first of which means that Venus has reached 
its greatest brightness ; the second, that the Earth is the nearest 
to the Sun that it will get, and the third, that there is a con- 
junction of Neptune and the Moon; and so on for every day 
of the year. 

Note: A good almanac for daily star information is the 
Old Farmers' Almanac, a copy of which you can get by sending 
11 cents to William Ware and Company, Boston, Mass. 



CHAPTER XII 
VALUABLE IKPOEMATION 

Photographing the Stars. — There are some interesting 
things you can do with an ordinary camera in the way of pho- 
tographing the stars. 

A camera is made up of three principal parts, and these are 
(1) a convex lens, which forms the image of the object to be 
photographed; (2) a light-tight box, which keeps out all the 
light except that which passes through the lens, and (3) a plate, 
or film holder, which holds the sensitive plate, or film, in the 
camera and keeps it perfectly dark until you are ready to have 
the image formed on it. 

The instant the lens is allowed to form an image on the 
sensitive plate, or film, we get out of the optics of photography 
and into the chemistry of it. 

The sensitive plate, or film, is coated with a thin layer of 
salts of silver and bromide, heated with gelatine and a little 
water, and when these substances are thoroughly mixed, an 
emulsion results, and this is spread on glass plates or on cellu- 
loid films. When the plate is exposed, that is, when the image 
has been formed on it, it is developed. The developing is done 
by placing the plate in a solution of pyrogallic acid, or hydro- 
quinone and water. 

The plate, or film, is now put in the fixing bath, which is 
simply a solution of hyposulphite of soda and water. This 
fixing bath prevents any further action of the light on the plate, 
or film. 

But the picture on the glass plate, or celluloid film, looks 
all samee like a Chinese chromo, for the light and dark parts 

185 



186 THE BOOK OF THE STARS 

are just the reverse of that of the object which was photo- 
graphed ; in other words, where the picture should be white, it is 
black, and where it should be black, it is white, and this is the 
reason it is called a negative. 

To get a picture of the object, as it looks to the eye, a sheet 
of paper, also coated with salts of silver, is laid flat on the nega- 

* NORTH STAR 




Fig. 180. — Camera Pointing to North Star. 

tive and held close to it in a printing frame when it is exposed 
to the light of the Sun. 

When the paper is printed dark enough by the Sun, it is 
toned to give it a pleasing color and fixed to make it last a 
long time, and when washed and dried the image of the object, 
true to life, is there, a wonderful record for all time, nearly. 

This then, briefly, is how the Sun, or other source of light, 
makes an image, how the image is fixed on a dry plate, or film, 
and how a picture is printed from the negative, and having 
found out this much let's see how we can make it do a little 
star work for us. 

There is not much we can do in the way of making pictures 
of the things in the sky with a small camera, but the few things 



VALUABLE INFORMATION 



187 



we can do are mighty interesting, and show the stars in a way 
you can never see them with the naked eye. 

To make star trails is one of these interesting things. First, 
set your camera on a tripod, or other firm support, and focus 
it on a tree or something as far off as you can see it in the day- 
time. Now, on a dark night, when there is no Moon, set your 
camera so that the lens is 
pointing directly at the 
North Star, as shown in Fig. 
180. Set the shutter of your 
camera for a time exposure 
and open it. 

You can go to bed now 
and let the stars work for 
you while you sleep, that is if 
you can get up before day- 
light the next morning, but 
if you cannot do this stay up 
as long as you can, three or 
four hours, anyway, before 
you close the shutter. 

Now, when you develop 
the plate, or film, and make a print from it you will have a 
record of the apparent path of the stars, as shown in Fig. 181, 
but which is, of course, due to the Earth turning round on its 
axis. If you set your camera with the lens pointing toward the 
ecliptic, that is, the path of the Sun, the star trails will be long, 
straight lines, and this will make another interesting record. 

By pointing your camera toward that part of the sky and 
during that time of the year when there are showers of meteors, 
and opening the shutter of your lens, you stand a chance, though 
it is not a very fat one, of catching one of these wily shooting 
stars on your plate, and if you do succeed — well, you will have 
a picture that is a curiosity. 

You can photograph the Sun with an ordinary camera and 
make his disk as large as you want to, but you will get nothing 




Fig. 181.— Star Trails. 



188 THE BOOK OF THE STARS 

more on your plate than a white spot. The Moon can likewise 
be photographed, but if you focus it sharp on the plate it will 
not be much larger than a mere point of light, and if you get a 
disk large enough to see there will only be a small white spot 
on your finished print. 

To make good photographs of the Sun, Moon and planets, a 
big telescope driven by clockwork to offset the turning of the 
Earth is needed. Such a telescope is called an equatorial tele- 
scope, and when it is set so that an object in the sky is in the 
field of view, it will remain right there as long as you want it, 
and when you make a photograph of the object it will be as 
sharp and as clear as though both it and the Earth were stand- 
ing perfectly still. 

If you think enough of the stars to try to photograph them 
with your little camera, I should say there is a very good chance 
of your being able to photograph them sometime through an 
equatorial telescope for all things come to the boy who wants 
them hard enough. 

What the Stars Are Made of .— To know what the stars are 
made of is to know more about them than men knew of the 
Earth a few hundred years ago. 

But just think of looking at a star like Aldebaran, which is 
so far away that it takes 45 years for its light to reach the 
Earth — light travels eleven million miles a minute — and then 
saying it is made of iron, and mercury and hydrogen and 
sodium and half a dozen other substances ! 

Now you ask, "How is it done ?" And I'll say with a glass 
prism, and then we'll have made a flying start. Now a glass 
prism is a three-sided piece of glass — the ends don't count — as 
shown in Fig. 144, and it is just as wonderful in its way as a 
lens is wonderful in its way. 

If you will hold a prism to your eye and look at the flame of a 
candle through it, you will see the flame in all the brilliant 
colors of the rainbow, and these bright colors form what is 
called a spectrum. 

Now make another experiment; cover a window, on which 



VALUABLE INFORMATION 



189 



the Sun shines, with a sheet of cardboard, in the middle of 
which yon have cnt a horizontal slit with a sharp knife, about 
1 inch long and y 25 inch wide. Make the room perfectly dark 
except for the light which conies in through the slit in the card- 
board, and set a prism in front of the slit, as shown in Fig. 145. 
The beam of sunlight which passes through the prism will be 
split up, or decomposed, as it is called, into the seven colors of 
the rainbow, but the colors will be much brighter. 

If you will fix another sheet of white cardboard in a vertical 
position so that the colors will 
shine on it in a band, the colors, 
beginning with red at the bot- 
tom, next orange, then yellow, 
green, blue, indigo and violet, 
will follow each other to the top 
bright and beautiful. These 
rainbow colors, spread out in a 
band on the screen, form what 
is called the solar spectrum, that 
is, the spectrum which is pro- 
duced by sunlight. 

While the spectrum in the 
above experiment is most beau- 
tifully colored, it is not a pure 
spectrum, for the colors overlap 

each other. In a pure spectrum each color is separately spaced 
off by dark lines, and these dark lines are just as important in 
finding out what the Sun and other stars are made of as the 
colors in between them. 

It is easy to produce a pure spectrum if you have a very 
narrow slit in the cardboard over the window, for all you have 
to do is to stand away from it five or six feet and look at the 
beam of light through a prism just as you did at the flame of the 
candle. This is the simplest form of a spectroscope, that is an 
instrument for splitting up the light of any object which is 
self-luminous, into a spectrum, as shown in Fig. 182. 





Fig. 182. — Boy Looking through 
Prism at Slit in Cardboard. j 



190 



THE BOOK OF THE STARS 



When you look at the sunlight streaming in through the slit 
in the cardboard you will see a number of dark lines separating 
the different colors. These dark lines are called Fraunhofer's 
lines, because Fraunhofer, who was a German telescope maker, 
was the first to show how important they are. The chief dark 
lines of the pure spectrum are known by the letters of the alpha- 
bet, and, like the colors they separate, they are always in the 
same place. They are shown in Fig. 183. 

Having found out a little about the spectrum and how it is 
formed by the Sun, let's find out next how it tells us what the 
Sun and the stars are made of. 

Now, in the pure spectrum there are a pair of lines close 
together and near the middle which are called the D lines — 



Eb F 



G HK 



RED ORANGE YELLOW GREEN &LUE VIOLET 

Fig. 183. — Fraunhofer's Lines. 



see Fig. 183 — and when a beam of sunlight is split up by a 
spectroscope, or rather by the prism of a spectroscope, there 
is always a bright yellow light between these D lines. 

There was a time, and not so very long ago, when no one 
had the faintest idea why the Sun produced this bright yellow 
light between the D lines when a candle flame nor any other 
kind of ordinary flame would make it. Then experimenters got 
busy burning every kind of substance they knew of and making 
the flame produce a spectrum, for some substances when burned 
make one color, or a number of colors, and other substances 
make another color, or combination of colors. 

Then one fine day some one burned a little sodium, and lo 
and behold there appeared the same bright yellow light between 
the D lines of the spectrum that the Sun makes. 

When this happened it did not take long for astronomers 



VALUABLE INFORMATION 191 

to guess that the bright yellow light between the D lines of the 
solar spectrum was made by the light of sodium which is burning 
in the Sun. 

In the same way iron and other metals and sodium and 
other substances which are heated until they become gases, and 
hydrogen and other gases which are aflame, produce certain col- 
ors between certain dark lines of the spectrum, and as the light 
from the Sun also produces the same identical colors between 
the same identical lines, it is known that the Sun contains these 
different substances which are burning up in it at white heat. 

It's the same thing with the stars. It makes no difference 
if the light is made by burning some substance a few inches 
away from the slit of the spectroscope, or whether it has traveled 




Fig. 184. — The Spectroscope. 

90 millions of miles from the Sun — which takes about 8% 
minutes, or 45 years for the light to reach it from Aldebaran, it 
always acts exactly in the same way; and so we know a good 
deal about the stuff the stars are made of. 

Let's see now, how a real spectroscope is made, for it isn't 
always convenient to have a pitch dark room, nor is it a very 
exact way to hold the prism to your eye when examining the 
light of burning sodium, or hydrogen gas, or other substances. 

The spectroscope is an instrument made so that the light of 
a substance burned at one end will pass through a prism and 
will form a spectrum on the retina of the eye at the other end. 
It is usually made up of two tubes mounted on a stand at an 
angle with the prism between them, as shown in Fig. 184. 

In the end of the first tube, which is called a collimator, a 
very narrow slit is cut, and it is at this end that the substance 



192 THE BOOK OF THE STARS 

is placed which is to be burned and whose light is to be split 
up and examined. 

A convex lens is fitted in the other end of the collimator, or 
first tube, so that the light after passing through the slit will 
then pass in a beam through the prism. The other tube — the 
one you look through — is called a telescope and in this one is 
fitted a convex object glass and an eyepiece which magnifies the 
spectrum made by the prism. 

When a camera is used to photograph the spectrum the eye- 
piece is taken out of the tube of the spectroscope and a little 
camera is put in its place. In this way the camera and the 
spectroscope are combined and this helps chemists to compare 
the spectra of different burning substances far better than they 
could do with the naked eye alone. 

To photograph the spectrum of the Sun the eyepiece of the 
big telescope is taken out and the end of the tube of the spectro- 
scope with the slit in it is fitted in its place. In making a pho- 
tograph of the spectrum of a star the slit is not needed, for the 
light of the star itself is but a mere point. 

In photographing the spectrum of the Sun and stars three 
wonderful instruments are combined, namely, the telescope, the 
spectroscope and the camera; perhaps I should have said four 
wonderful instruments, for without the brain of a genius using 
them the Sun and stars never would have given up their secrets. 



APPENDICES 

APPENDIX A 

According to the official Handbook of the Boy Scouts, if you 
are a Scout and want to win a merit badge for starcraft, you 
must 

(1) Have a general knowledge of the nature of the stars and 
planets. 

(a) By the nature of the stars and planets is meant their 
colors and what they are made of. Their sizes and their dis- 
tances from the Earth in a general way may also be included. 

(b) It is easy to tell the color of both the stars and the 
planets by looking at them, or by looking them up in the fore- 
going chapters. 

(c) The spectroscope shows that the stars are made of metals 
and gases and other substances which we have on Earth. The 
planets are probably made of the same kinds of metals, gases 
and substances as those which form the Earth, but there is no 
way of proving this, for the planets shine by reflected light, and 
in this case the spectroscope is of little use. 

(d) The stars are known to be suns as large or larger than 
our Sun; while the planets are about as large as our Earth — 
some smaller and some larger. 

(e) All of the planets are within 2,800 millions of miles of 
the Earth, while the nearest star, except our Sun, is 25 tril- 
lions of miles from the Earth, or 8,000 times as far away. 

(2) Have a general knowledge of the movements of the 
stars and planets. 

(a) While all the stars revolve in orbits and are moving 
193 



194 APPENDICES 

through space at high speed, they are so far away from us that 
they seem to be fixed and for all practical purposes they may 
be considered to be fixed in their positions. 

(b) All the planets turn on their own axes and travel in 
orbits round the Sun. 

(3) Point out and name 12 principal constellations. 

(a) Twelve easy constellations are: (1) The Big Dipper; 
(2) The Little Dipper; (3) Cassiopeia; (4) Pegasus; (5) 
Orion; (6) Auriga and (7) Taurus, all of which are shown in 
Chapters I and II; (8) Gemini; (9) Leo; (10) Virgo; (11) 
The Scorpion, and (12) Sagittarius, which are constellations of 
the zodiac, and are shown in Chapter XL 

(4) Find the North by means of other stars than the Pole' 
Star (which is the North Star) in case that star is obscured by 
clouds. 

(a) This can be done by finding the constellation of Cassio- 
peia, see Chapter I; and also by Pegasus; Auriga and Orion, as 
explained in Chapter II. 

(5) Have a general knowledge of the positions and move- 
ments of the Earth, Sun, Moon, and the Planets; and of tides, 
eclipses, meteors and comets. 

(a) By reading the chapters on the Sun, Planets, Earth 
and Moon and 

(b) Other things in the sky carefully, you will be able to 
pass the requirements named in No. 5. 

(6) Plot on at least two nights per month for six months 
the positions of all naked-eye planets visible between sundown 
and one hour thereafter. The plot of each planet shall contain 
at least three fixed stars with their names or designations; colors 
of planets and stars are to be recorded as observed. 

(a) How to plot the position of a planet is fully explained 
in the chapter on Planets, but you should also read the one on 
The Stars of the Zodiac. 



APPENDIX B 

Figures. — When explaining the positions and forms of 
things, it is often necessary to use certain terms and figures, 
that is to say, lines which are either real or imaginary, but which 
can be drawn on paper. See Fig. 185. 

(1) A straight line is, of course, a line which runs uni- 
formly in the same direction, and which is regular and without 
curves. A straight line is the shortest distance between two 
points. (2) When we say that lines are parallel, we mean that 
they lie so that every part of each is equally spaced from the 
other. (3) A line is horizontal when it is parallel with the 
level surface of the Earth under it. (4) A line is perpendicular 
to the surface of the Earth when it is plumb, that is, in a line 
with the center of the Earth. (5) A vertical line generally 
means a plumb line. (6) A right angle is formed when a verti- 
cal, or a perpendicular, line meets a horizontal line. (7) A 
circle is a curved line, all points of which are equally distant 
from its center. Circular means round like a circle. (8) By 
diameter is meant a straight line drawn from one side, or half 
of a circle, to the opposite side through its center. (9) The 
radius of a circle is a straight line drawn from the center of a 
circle, or a ball, to its surface. (10) A ring is a disk or object 
having a circular hole cut in its center. (11) An arc of a circle 
is a part of a circle. (12) A quarter circle is, of course, the 
one-fourth part of a circle. (13) A tangent is the point on a 
circle where a line meets it but does not cut it. (14) An el- 
lipse is an oval figure, drawn on a plane surface. (15) The 
equator is a circle which divides the Earth or other ball into 
equal parts, and is 90 degrees from the north and south poles. 

195 



196 



APPENDICES 



(16) The ecliptic is a circle round the Earth which is in the- 
same plane with the equator of the Sun. 




HORIZONTAL LINE 



i^ 



C/THIS LINE REPRESENTS 
THE LEVEL SURFACE 




OF THE EARTH 



THE ECLIPTIC x A CIRCLE 

AND THE EQUATOR A RC,OR ARC OF CIRCLE 




RADIUS TANGENT OPPOSITION 

Fig^ 185. — Geometrical Figures. 



APPENDIX C 
THE GEEEK ALPHABET 

Many of the brighter stars have names, as Aldebaran, Ca- 
pella, Sirius, etc., but astronomers now indicate the stars of a 
constellation by the letters of the Greek alphabet. Thus the 
brightest star of a constellation is called a, that is, Alpha, the 
next brightest ft, which is Beta, and so on until every star in 
the constellation has been given a letter. 

.The following is the Greek alphabet : 

o Alpha v Eta "Nu t Tau 

|8 Beta e Theta r Xi (Zi) « Upsilon 

7 Gamma t Iota ° Omi'cron <P Phi 

5 Delta k Kappa t Pi x Chi 

« Epsilon X Lambda p Rho ^ Psi 

£ Zeta n Mu <r Sigma « Omega 



197 



APPENDIX D 
STAE TESTS FOR EYESIGHT 

There are a number of stars which are considered to be good 
tests for the seeing power of the eyes. The faint stars of the 
Pleiades are a fine test of this kind; but usually these tests are 
double stars and while one will be bright and easily seen its 
companion will be very faint. The test is to see the faint one, 
and if you can see it you may consider you have very good eye- 
sight. 

Eyesight tests are given on the following pages: 

Page Page 

11 — Mizar and Alcor 119 — Nebula in Orion 

34 — Spots on the Sun 150 — Epsilon in Lyra 

94 — Grimaldi on the Moon 150 — Pleiades 

182 — Alpha and Beta in Capricornus 



198 



APPENDIX E 

MAGNITUDE OF STAKS 

There are not nearly as many stars in the sky as yon might 
at first suppose. The stars are divided into magnitudes, that is, 
according to their brightness. Stars of the first magnitude are 
the brightest stars; stars of the second magnitude are second 
brightest, and so on. The total number of stars which 
can be seen with the naked eye on any one night in the United 
States is probably not more than 3,000. The following table 
gives the number of stars of the different magnitudes up to and 
including the sixth: 

Magnitudes Number of Stars 

1st 20 

2nd about 65 

3rd about 200 

4th about 500 

5th about 1,400 

6th about 5,000 



199 



APPENDIX F 



FIEST MAGNITUDE STAES 



The brightness of a star is known by its magnitude. A star 
of the first magnitude is one of the 20 brightest stars, and is 
2% times as bright as a star of the second magnitude; a star 
of the second magnitude is 2% times as bright as a star of the 
third magnitude ; and so on. A star of the sixth magnitude can 
just be seen with the naked eye on a clear night when there is 
no Moon. 

Fourteen of the twenty first magnitude stars can be seen in 
the northern sky, and these are: 



NAME OF STAR 



NAME OF CONSTELLATION 



1. Sirius, the Dog Star, 3 


n Canis Major 


2. Capella ' 


Auriga 


3. Arcturus 


Bootis 


4. Vega 


1 Lyra 


5. Rigel (/5) 


Orion 


6. Procyon 


Canis Minor 


7. Betelgeux (a) 


1 Orion 


8. Altair ' 


Aquila 


9. Aldebaran * 


Taurus 


10. Spica ' 


Virgo 


11. Antares ' 


Scorpius 


12. Pollux ' 


Gemini 


13. Regulus ' 


Leo 


14. Deneb ' 


i Cygnus 



200 



APPENDIX Gr 
CONSTELLATIONS HAVING FIRST MAGNITUDE STARS 

The following important constellations are not described in 
the foregoing chapters of this book. They can be found, though, 
without trouble, since a star of the first magnitude is located in 
each. 

Canis Major, the Big Dog, is a winter constellation, and can 
be seen on your meridian at 9 o'clock P. M. in February. Look 
for it in the southern sky and you will quickly find it because 
of the dazzling brightness of Sirius, the Dog Star. 

Bootes (pronounced Bo-d'-tes), the Bear Leader, is a sum- 
mer constellation, and can be seen on the meridian at 9 o'clock 
P. M. in June. It is just this side of the ecliptic, or path of the 
Sun. It lies between a crown of stars and Virgo. You can't 
miss it, for midway is Arcturus, a red star of the first magnitude. 

Lyra, the Lyre. — Is a summer constellation, and can be seen 
on the meridian at 9 o'clock P. M. in August. Look for it al- 
most overhead, and you can't mistake it, for three bright stars, 
of which Vega is one, form a triangle. 

Canis Minor. — The Little Dog : is a spring constellation, and 
can be seen on the meridian at 9 o'clock P. M. in March. It lies 
to the south of the constellation of Gemini, the Twins, and Can- 
cer, the Crab. In it you will see Procyon, the Little Dog Star. 

Aquila, the Eagle. — Is a summer constellation, and can be 
seen on the meridian in August. Look for it south of Lyra, 
and far to the west of Pegasus. The star that put Aquila on the 
map is Altair. 

Cygnus, the Swan. — Is also a summer constellation, and 
201 



202 APPENDICES 

can be seen on your meridian at 9 o'clock P. M. in September. 
You will find it north of Pegasus and east of Lyra, and in it 
you will see the Northern Cross clearly traced out with seven 
stars, the brightest one being Deneb, a first magnitude star. 



APPENDIX H 
COLORED STARS 

The following are a few stars which are highly colored — all 
the stars in the following list are first magnitude stars except 
the North Star: 

White Stars: Sirius, Regulus, Vega, and Polaris, the 
North Star. 

Blue Stars: Capella, KigeL, Procyon and Spica. 

Red Stars: Aldebaran, Antares, and Betelgeux. 

Green Stars: Altair and Deneb. 

Yellow Stars: The Sun and Arcturus. 



203 



APPENDIX I 
DOUBLE STARS 

When two stars are very close together they form what is 
called a double star, but a real double star is one that cannot be 
resolved, that is separated, into two stars without the aid of a 
telescope. 

The North Star; Rigel, Castor; Procyon and Sirius, are all 
famous double stars. 



204 



APPENDIX J 

VARIABLE STARS 

A variable star is one whose brightness changes from time to 
time. There are about 400 variable stars known, though very 
few of them can be seen with the naked eye. There are different 
reasons given for a star varying in brightness. Our Sun is a 
variable star, and we are told that this is due to his spots. 
Sirius, the Dog Star, is a double star, but instead of having a 
bright companion it has a dark one (see Appendix K, invisible 
stars), and this dark star gets in between us and the bright star 
every once in a while, or partly in the way, and so cuts off 
part of the light from Sirius. Again a double star formed of 
two bright stars which revolve round each other, as many double 
stars do, may eclipse one another, and this would cause a change 
in brightness. Here, then, are three good reasons for a star be- 
ing variable. 

The following variables can be seen with the naked eye: 

Betelgeux, in Orion. 

Alpha Cassiopeia, that is, the brightest star in Cassiopeia. 

Beta Lyra, that is, the second brightest star in Lyra, and 

Beta Pegasus, that is, the second brightest star in Pegasus. 



205 



APPENDIX K 
INVISIBLE OR DARK STARS 

Stars are born, live and die, just like human beings. All the 
stars, including the Sun, are either in the process of making, 
are at their brightest brilliancy, are dying out, or are cold and 
dead. 

Procyon is attended by a dark companion, which has never 
been seen, but whose presence is known by its attraction on 
Procyon. 

Sirius is attended by a dark companion, whose presence was 
known by its pull on Sirius 16 years before it was seen through 
a telescope. 



206 



APPENDIX L 
THE EQUATION OF TIME 

As we have seen in Chapter X every day of the year is exactly 
24 hours long by our clock time. The time by the Sun is usually 
either ahead or behind clock time. The difference between 

TABLE OF THE EQUATION OF TIME 



Day of Month 


January 


February 


March 


April 


May 


June 


1 


m 

S 3 
S 5 
S 7 
S 9 
S 11 
S 12 
S 13 


s 
31 

49 
59 
49 
24 
39 
35 


m 

S 13 

S 14 
S 14 
S 14 
S 13 
S 13 
S 12 


s 

44 
15 
27 
19 
52 
10 
13 


m 

S 12 

S 11 
S 10 
S 8 
S 7 
S 5 
S 4 


s 

37 

33 

19 

57 

28 

56 

24 


m S 
S 4 6 
S 2 37 
S 1 14 
F 4 
F 1 12 
F 2 10 
F 2 56 


m 
F 2 
F 3 
F 3 
F 3 
F 3 
F 3 
F 2 


5 

56 
27 
45 
48 
38 
15 
39 


m S 
F 2 30 


6 


F 1 41 


11 


F 44 


16 


S 18 


21 


S 1 23 


26 


S 2 27 


31 


S 3 38 







Day of Month 



July 



August 



September 



1 

6 
11 
16 
21 
26 
31 



s 

3 28 

4 24 

5 11 

5 46 
6 

6 11 
6 12 



S 24 



S 
F 
F 
F 
F 
F 
F10 



6 45 
8 29 



m 

F 10 
F 11 
F 13 
F14 
F 15 
F15 
F 16 



F16 
F16 
F15 
F15 
F14 
F12 
Fll 



m 
Fll 
F 9 



3 
3 

6 51 



30 
2 



28 
2 55 



clock time and Sun time is called the equation of time, and a 
table to show how many minutes and seconds the Sun is fast 
or slow, according to clock time, is given in the preceding table, 

:o 7 



208 APPENDICES 

taken from "The New Astronomy/' by Professor Todd, who has 
kindly permitted me to use it here. In the table S means that 
the Sun is slow, that is, that the Sun does not cross the meridian 
until after the clock shows noon, and F means that the Sun is 
fast, that is, that the Sun has crossed the meridian before the 
clock shows noon. M means minutes, and S means seconds 
above the figures. 



APPENDIX M 



THE KULLMER STAR FINDER 



The star finder shown in the picture was invented by Dr. C. 
J. Kullmer, of Syracuse, N. Y., and has been highly praised by 
many great astron- 
omers. 

You should 
own one if possible, 
for you do not need 
to know anything 
about the stars to 
operate it. It is 
mounted on the 
principle of a big 
telescope, but it is 
a naked-eye instru- 
ment, a n arrow 
taking the place of 
the telescope. 

The finder is 
placed on a table, 
or other level sur- 
face, with the dial 
facing north. Then 
the pointer and 
dial are set for the 
day and hour when 
you want to find the position in the sky of a certain constella- 
tion. The indicator is turned to the name of the constellation 
on the dial, and this also tells the direction to set the arrow. 

209 




Fig. 186. — Kullmer Star Finder. 



210 APPENDICES 

This is all there is to it and the arrow points right at the 
group of stars you want, whether they are above the horizon or 
not. 

The finder can be used for many purposes, and it is a won- 
derful aid in making out in the sky the path of the stars, Sun, 
Moon and planets, and when they rise and set. In fact, it is a 
complete observatory on a small scale. Its cost is only $5.00. 



APPENDIX N 
THE ELLIS SEASONAL TWILIGHT CHART 

A useful chart, designed by Miss E. Eebecca Ellis, of Welles- 
ley College, Wellesley, Mass. It makes clear the changes in the 
lengths of the day, the phenomena of the seasons, etc. Its price 
is $1.00. 



211 



DEFINITIONS OF SOME WORDS AND TERMS USED 
IN THIS BOOK 



Action. The way in which a 
thing works. 

Affect. To act upon ; to change ; 
to be moved or influenced by. 

Almanac. A pamphlet or book 
containing tables showing the 
days of the year; also the 
time the Sun and Moon rise 
and set; the conjunctions, 
eclipses and other informa- 
tion concerning the things in 
the sky. The word almanac 
is supposed to be derived from 
the Arabic article al and the 
verb manac, which means to 
count. 

Angular measurements. See 
Appendix B. 

Aphelion. The point where a 
planet or a comet is farthest 
away from the sun. 

Apparent. To seem real. The 
motion of the Sun round the 
Earth is only apparent, for as 
we know it is the Earth 
which turns round on its axis 
instead. 

Arc. See Appendix B. 

Arc of circle. See Appendix B. 

Aspect. (1) Any curious ap- 
pearance of an object, espe- 
cially if the object changes in 
appearance. (2) The figure 



formed by a planet with the 
stars of the constellation 
which it is in. 

Astrologer. One who forecasts 
the life of a person on the 
supposition that the stars 
control it. 

Astronomer. One who is skilled 
in seeing the stars and who 
knows them. 

Atom. A very small particle of 
matter. See Molecule; Matter. 

Attract. To pull toward. The 
attraction of the Sun and the 
Earth for each other is due 
to gravitation. 

Attraction. A force which pulls 
one body to another. 

Attraction of Gravitation. A 
force called gravity which 
pulls all bodies to each other. 

Auditory nerve. A nerve that 
carries the impressions of 
sound which reach the ear to 
the brain. 

Aurora borealis. The Northern 
Lights. A glowing light ef- 
fect which takes place in the 
Arctic Circle. It can often be 
seen from our Northern 
States and sometimes from 
the Southern States. The 



213 



214 



THE BOOK OF THE STARS 



same kind of lights appear in 
the Antarctic Circle. These 
Southern Lights are called 
Aurora Australis. 

Axes. Plural of axis. 

Axis. An imaginary line on 
which a body turns. 

Axis of rotation. An imagin- 
ary line round which anything 
turns or spins. 

Axle. A wood or metal rod on 
which one or more wheels 
turn, or it may turn with the 
wheel or wheels. 

Badge of merit. A badge 
awarded by the organization 
of Boy Scouts to members 
who can show a certain 
amount of skill in doing 
certain things. See Appen- 
dix A. 

Band. (1) A flat strip of any 
material, or (2) such a strip 
whose ends are joined to- 
gether. 

Beam. Rays of light which 
are parallel. See Ray. 

Bearing. (1) A piece of metal, 
or a bit of agate or other jew- 
el, on which a pivot, spindle or 
shaft turns. (2) One's posi- 
tion as found by the Sun or 
stars, or by the compass, sex- 
tant or other means. 

Body. Any separate and dis- 
tinct amount of matter when 
held together. The Sun and 
Moon are heavenly bodies. 

Degree. (1) The 360th part of 
a circle. (2) Indicated by 
this sign °. 

Device. (1) An apparatus or 
instrument or any part there- 



of. (2) Any arrangement for 
producing a given result. 

Diagram. A sort of shorthand 
picture of an apparatus or 
part of an apparatus. It is 
used to show in the sim- 
plest and clearest manner the 
construction of an appara- 
tus. 

Diameter. See Appendix B. 

Direct line. A straight line. 

Disk. (1) A circular plane or 
flat surface. Since the Sun, 
Moon and planets seem to be 
flat their surfaces are called 
disks. (2) Flat and circular 
like a coin. 

Dog days. So called from the 
fact that Sirius, the Dog 
Star, rises at the same time 
as the Sun. 

Ecliptic. See Appendix B. 

Elastic. (1) A body that will 
stretch and return to its origi- 
nal size. (2) A thin piece of 
rubber. 

Ellipse. See Appendix B. 

Equator. See Appendix B. 

Equatorial. Having to do with 
or affected by the equator. 

Equatorial telescope. A tele- 
scope so mounted that its 
principal axis is parallel with 
the equator and so arranged 
that it will follow a star by 
affecting the motion of the 
earth. 

Evening Star. A planet which 
can be seen in the west just 
after the sun sets. 

Fixed. (1) Fastened to se- 
curely. (2) The stars are 
called fixed because they 



DEFINITIONS OF WORDS AND TERMS 215 



never seem to change their 
positions. 

Forecast. A prediction of some 
future event. A forecast may- 
be founded on fancy or on 
fact. A horoscope of a per- 
son is a forecast based on the 
fancy of an astrologer. A 
weather forecast is founded 
on the action of a barometer, 
and even then the forecast is 
uncertain enough. Forecasts 
of the time of eclipses, the re- 
turn of comets and the like 
are founded on cold scientific 
facts and hence come true at 
exactly the calculated time. 

Frequency. A number of events 
which occur at regular inter- 
vals in a given time. 

Gas. That form of matter 
which is like air. Gases re- 
main in the gaseous state at 
ordinary temperatures. Gases 
have a tendency to expand 
without limit. See Vapor. 

Generate. To produce. To set 
up; as a battery generates a 
current; the Sun generates 
power. 

Gravitation. The force which 
attracts all bodies near the 
Earth to it and all bodies to 
each other. 

Heavens. The sky. The space 
as far as the eye can see 
about the Earth. The space 
in which the stars and their 
planetary systems move. 

Horizontal. See Fig. 185. 

Horoscope. A forecast of the 
future of a person made by 
an astrologer who pretends to 



read the future from the as- 
pect or position of the 
planets and stars. 

Hyperbola. See Fig. 129. 

Hypothesis. See Idea. 

Idea. A notion of a plan or 
scheme which may be more 
or less vague. Supposition. A 
clearer conception of a plan 
or scheme which is based on 
such facts as may be thought 
of. Hypothesis. A plan or 
scheme assumed to be true 
and carefully reasoned out 
from all the facts obtainable. 
Theory. A plan or scheme 
which has been proved true 
by experiment, examination 
or comparison. 

Illusion. An image which de- 
ceives the eye. The other 
senses can also be deceived by 
illusions. 

Impact. Coming together of 
two objects. 

Impress. To form on, or to af- 
fect, as light waves impress a 
dry plate. 

Indicate. To show. To point 
out. 

Indicator. That which points 
out or shows something. 

Limb. The edge of the Sun, 
Moon or Planets. 

Lore. Learning on any subject. 

Lunar. Of, or having to do with 
the Moon. 

Magnetic lines of force. The 
force of magnetism acting in 
and around a magnet. 

Magnetic storm. The Earth is 
a great magnet and some- 
times when sun spots of un- 



216 



THE BOOK OF THE STARS 



usual size or numbers appear, 
the magnetic lines of force 
of the Earth are violently af- 
fected. This is called a mag- 
netic storm. 

Mass. (1) The size of a thing. 
(2) A lot of molecules or par- 
ticles of matter brought and 
held together. 

Matter. The substance of which 
a thing is formed. A molecule 
of matter is made up of 
atoms, and a mass is a lot of 
molecules held together by 
some attractive force. 

Mercury. (1) The name of the 
planet nearest the Sun. (2) 
A silver white liquid metal. 

Molecule. The smallest part of 
matter that can exist sepa- 
rately without the substance 
it forms being destroyed. 

Morning Star. A planet which 
can be seen in the east just 
before the Sun rises. 

Morse code. A telegraph code 
of dots and dashes invented 
by Samuel F. B. Morse. The 
Morse Code is used for tele- 
graph and heliograph signal- 
ing. 

Motion. Anything that changes 
position. There are two kinds 
of motion (a) simple motion 
and (b) compound motion. 
Simple motion can be either 
translated or rotary, while 
compound motion is both 
translated and rotary, so that 
while a body is being trans- 
lated, or moved through 
space, it is also rotating on its 
axis. The Sun and planets, 



then, have compound mo- 
tions. 

Nature. Everything contained 
in space that has not been 
shaped by human hands. 

Nautical almanac. The Amer- 
ican Nautical Almanac is a 
book of the stars published 
by the Bureau of Navigation 
of the United States. It is 
published three years in ad- 
vance and is sold by the Su- 
perintendent of Documents, 
Washington, D. C, at 30 cents 
per copy. This is designed 
chiefly for the use of navi- 
gators of ships. It gives the 
exact positions of the Sun, 
Moon and planets and much 
other astronomical informa- 
tion. It is based upon the cal- 
culations made by the United 
States Naval Observatory ; 
these are printed in the Nauti- 
cal Almanac, and on this all 
other almanacs are based. 

Northern lights. See Aurora 
Borealis. 

Obscured. Hidden from sight. 

Official Handbook of the Boy 
Scouts. A book published by 
the organization of Boy 
Scouts and which contains the 
rules and regulations of that 
organization and the require- 
ments they must meet in or- 
der to win merit badges. 

Offset. To equal; to balance. 

Opposition. See Appendix. 

Optic Nerve. The nerve that 
carries the impression of light 
received by the eye to the 
brain. 



DEFINITIONS OF WORDS AND TERMS 21T 



Orbit. The path followed by a 
body. Atoms have orbits as 
well as the stars. The paths 
followed by planets and 
comets round the Sun. 

Parabola. See Fig. 129. 

Parallel. See Appendix B. 

Particle. A bit of matter. A 
particle may be a bit of mat- 
ter which can be seen or it 
may mean an amount so small 
that it cannot be seen. 

Pencil. A group of rays from 
the same source of light. See 
Beam. See Ray. 

Pendulum. A body suspended 
from a fixed point and free to 
swing in any direction. 

Perihelion. The point where a 
planet or a comet is nearest 
the Sun. As the orbit of a 
planet is an ellipse and the 
Sun is in one of the foci ; that 
is near one end, a planet 
comes nearest to the Sun 
when at this end of the el- 
lipse; and when the planet is 
at the other end of its orbit, 
it is farthest away. See 
Aphelion. 

Period. A certain interval of 
time which is marked by 
a repeated occurrence. The 
period of the Earth round its 
axis is about 24 hours. Its 
period around the Sun is 365 
days. 

Periodic. The time that elapses 
between two recurring events ; 
as a periodic comet. 

Perpendicular. See Appendix B. 

Phase. One of the peculiar as- 
pects of a heavenly body; as 



the phases of the Moon, or 
the phases of Venus. 

Pivot. A pin, spindle or shaft 
on which a wheel, lever or de- 
vice rotates or is rotated. 

Plane. A level surface, as a 
table top. 

Point. A sharp end. A start- 
ing place. 

Pores. Minute spaces which 
separate the molecules of a 
substance. 

Position. The place of a thing 
when compared to the places 
of other things. 

Precede. To go ahead of. That 
which is before. 

Precession. The act of going 
ahead or preceding. When a 
revolving body such as a spin- 
ning top or the Earth is acted 
upon by forces which tend to 
change the direction of its 
axis. This change in the di- 
rection of its axis is called 
precessional motion^ The pole 
of the equator of the Earth 
makes a complete turn round 
the pole of the ecliptic in a 
little over 25,000 years and 
this change in the direction 
of the axis of the Earth 
causes the points of the equi- 
nox, that is the places where 
the ecliptic and the equator 
cross each other to move 
slowly from west to east and 
this is termed the precession 
of the equinoxes. 

Prediction. To foretell; to fore- 
cast. Predictions may be 
based on fancy or founded on 
fact. 



218 



THE BOOK OF THE STARS 



Principal. The chief one; the 
most important. 

Principle. The cause of a re- 
sult. That on which a thing 
is based. 

Process. (1) The way of work- 
ing. (2) The course of pro- 
cedure. 

Produce. In astronomy the 
word produce means the 
lengthening of a line. It is a 
mathematical term. 

Protractor. See Fig. 9S. 

Quarter circle. See Appendix B. 

Ray. (1) A single line of light 
or heat. (2) The path of 
light and heat. 

Relative position. The position 
of a thing when compared 
with the position of some- 
thing else. See Position. 

Revolution. The turning of a 
thing completely round on its 
axis. 

Revolve. (1) To turn com- 
pletly round a circle. (2) To 
turn on an axis, as a top, or 
the Earth. 

Rigid. Firm, that which can- 
not be easily moved out of its 
place. 

Ring. See Appendix B. 

Rise. To come into sight above 
the horizon, as the Moon rises. 

Rotate. To turn completely 
round on an axis like a top or 
the Earth. 

Rotary. Turning completely 
round on an axis, like a top 
or the Earth. 

Roughly. Not exactly; nearly 
enough for practical purposes. 

Schedule. (1) A tabulated 



statement giving items con- 
cerning a subject. (2) A 
timetable of any kind. 

Seeing. To look at. The word 
seeing in starcraft means to 
observe the stars. Good see- 
ing is to observe the stars 
when the atmosphere is per- 
fectly clear. 

Seems. Something which ap- 
parently is true and yet is not 
true. 

Sensation. The action of one of 
the senses when excited by 
some change in matter. Light 
falling on the retina of the 
eye produces the sensation of 
light and color in the brain. 

Set. To sink from sight below 
the horizon; as the Sun sets. 

Sight. The power to see. See 
Sighting. 

Sighting. To get the eye and 
two other objects, such as a 
telescope and a star, in a line, 
as to sight Jupiter with a 
telescope. 

Sign. A mark, figure or letter 
which astronomers have 
agreed to use to represent 
certain stars, aspects of stars, 
parts of the zodiac, etc. 

Solar. That which is of, or has 
to do with the Sun. 

Spring stars. The stars which 
can be seen best during the 
spring months. 

Star chart. A map of the posi- 
tions of the stars. 

Starcraft. Useful knowledge of 
the stars. Skill shown in 
making the stars serve useful 
purposes. 



DEFINITIONS OF WORDS AND TERMS 219 



Star finder. A device of any 
kind which will enable an un- 
skilled person to find the 
planets or constellations. 

Star-lore. Learning concerning 
the mythology of the stars. 

Summer stars. The stars which 
can best be seen during the 
summer months. 

Supposition. See Idea. 

Tangent. See Appendix B. 

Tangent line. See Appendix B. 

Telegraph code. The alphabet 
of dots and dashes. 

Test. To try out. To examine, 
compare or make an experi- 
ment which will give a needed 
proof. 

Theory. See Idea. 

Thumb tack. A short, thin, 
sharp-pointed tack with a 
large flat head which permits 
it to be easily pushed into a 
board with the thumb. It is 
used by draftsmen for fasten- 
ing paper to drawing boards. 

Tilting. Leaning from a ver- 
tical or plumb line. The axis 
of the Earth is tilted from 
the perpendicular 23y 2 de- 
grees; this throws its equator 
out of plane with that of the 
sun, and the circle around the 
Earth that is in plane with 
the Sun is called the ecliptic. 

Transparent. Said of any sub- 
stance through which light 
can pass easily. Anything 
that may be seen through. 

Twinkle. To blink. To flash 
with varying brightness. The 
twinkling of stars is caused 
by the atmosphere. 



Uniform. Being the same all 
through or all along. 

Vapor. A gas produced from a 
liquid or a solid and which re- 
turns to its original form at 
ordinary temperatures. See 
Gas. 

Vertical. See Appendix B. 

Vibration. A to-and-fro move- 
ment, as the vibration of a 
particle of matter. A con- 
stant to-and-fro movement 
over the same line. 

Visible. That which the eye 
can see. 

Wane. To gradually grow small- 
er. Said of the Moon. 

Wax. To gradually grow larger. 
Said of the Moon. 

Winter Stars. The stars which 
can best be seen during the 
winter months. 

Wireless Messages. Messages 
which are sent and received 
by wireless telegraph stations. 

Wireless system. An apparatus 
for sending and receiving mes- 
sages by wireless telegraph. 

Your meridian. The line run- 
ning due north and south in 
the sky directly over your 
head. A meridian of this 
kind is called a- celestial me- 
ridian. 

Zodiacal lights. A faint glow- 
ing light which may be seen 
above the western horizon 
just after twilight during the 
clear evenings of winter and 
spring. It can also be seen just 
before daybreak during the 
clear mornings of summer 
and autumn. 



INDEX 



Air, thickness of, around Earth, 

125. 
Air waves, 125. 
Alcor, in the Big Dipper, 11. 

and Mizar through a glass, 150. 
Aldebaran in Taurus, 26, 28. 
Almanac, 171. 

how to read, 182. 

Old Farmers', 184. 

signs in, 183. 

use of, for finding planets, 61. 
Alpha Centaurus nearest star, 118. 
Alphabet, Greek, 197. 

Morse, 39. 
Andromeda, great nebula in, 119. 
Annular eclipse of the Sun, 112. 
Antares in Scorpio, 180. 
Apennines on the Moon, 146. 
Apparent noon, 154. 
Apparent solar day, 154. 
Apparent time, 152. 
Aquarius, the Water Bearer, con- 
stellation of, 63. 

the Water Man, 173. 
Aquila, the Eagle, 201. 
Arab test for eyesight, 11. 
Are defined, 194. 
Arctic day and Sun, 87. 
Arcturus in Bootes, 28. 
Aries, the Bam, 63, 175. 
Aristarchus on the Moon, 146. 
Ass's Colts in Cancer, 176. 
Asteroids, 47, 54. 
Astrologer's horoscopes, 180. 
Atoms, vibration of, 123. 
Auditory nerve, 125. 



Autumn, 74. 
Autumnal equinox, 178. 
Auriga, Capella in, 24. 
Auriga, the Charioteer, 23. 

constellation of, 23. 

of the Greeks, 24. 

the Shepherd, 24. 

Barometer, a simple, 35. 
Barometric pressure, 35. 
Belt of Orion, 21. 
Beta Pegasus, 18. 
Betelgeux in Orion, 28. 
Big Dipper, the, 2, 4. 

Alcor in the, 11. 

how to tell time by the, 12. 

Mizar in the, 11. 

pointer stars of, 10. 

position of, in autumn, 3. 
in summer, 11. 
in spring, 10. 
in winter, 9. 

through a telescope, 149. 
Bootis, the Bear Leader, 201. 
Boxing the compass, 78. 
Boy Scout, merit badge for, 193, 
Boy Scouts' Handbook, 193. 
Brain of a genius, 192. 
Bull of Light, the, 26. 
Burning lens, 37. 

Camera, how it is made, 185. 
Cancer, the Crab, 176. 
Candle flame, 30. 
Canis Major, constellation of, 28, 
201. 



221 



222 



INDEX 



Canis Minor, the Little Dog, 201. 
Capella, how to find the North 

with, 24. 
Cardinal points of a compass, 78. 
Cassiopeia of the Arabians, 16. 

constellation of, 14. 
Castor and Pollux in Gemini, 176. 
Cave man, how he marked time, 

152. 
Central time, 160. 
Centrifugal force, 58, 90. 
Chromosphere, the Sun's, 32. 
Chronograph, how made and used, 

162. 
Chronometer, use of, to find longi- 
tude, 85. 
Circle defined, 194. 
Colored stars, 202. 
Colored sun glasses, 30. 
Colors, how they are made, 123, 

129. 
Combustion, what it is, 123. 
Comet, breaking up of, 116. 

coma of a, 113. 

Halley's, 115. 

how to find a, 112. 

nucleus of a, 113. 

tail of a, 113, 116. 
Comets, laws of, 114. 

number of, 116. 

paths of, 113. 

speed of, 115. 
Compass, boxing the, 78. 

cardinal points of a, 78. 

dial, mariner 's, 78. 

how to make a simple, 77. 

mariner's, 78. 

pocket, 78. 
Concave lens, 134. 
Constellations: Aquarius, the Wa- 
ter Bearer, 63. 

Aquila, 201. 

Aries, the Earn, 63, 173, 175. 



Constellations: Auriga, 23. 

Big Dipper, 6. 

Bootis, 201. 

Cancer, the Crab, 176. 

Canis Major, 28, 201. 

Cassiopeia, 14. 

Cygnus, 201. 

Flying Horse, 19. 

Gemini, the Twins, 63, 176. 

Great Bear, 6. 

Great Square of Pegasus, 17. 

having first magnitude stars, 
201. 

Libra, the Balance, 178. 

Little Bear, 16. 

Little Dipper, 15. 

Leo, the Lion, 177. 

Lyre, 201. 

Mighty Orion, 20. 

Northern Cross, 202. 

Pisces, the Fishes, 63, 174. 

Pleiades, 26. 

Plough, 6. 

Sagittarius, the Archer, 180 

Scorpio, the Scorpion, 180. 

six chief, 27. 

Taurus, the Bull, 24, 175. 

twelve chief, 196. 

Ursa Major, 6. 

Ursa Minor, 17. 

Virgo, the Virgin, 177. 

what they mean, 14. 

Zodiac, 168. 
Convex lens, 133. 
Copernicus on the Moon, 148. 
Corona of the Sun, 33. 
Crescent Moon, 93. 
Cycle of the Seasons, 75. 
Cygnus, the Swan, 201. 

Dark stars, 206. 
Day, solar, 154. 

when it begins and ends, 152. 



INDEX 



223 



Definitions of words used in star- 
craft, 213. 

Degrees, dividing a circle into, 156. 
Earth divided into, 81. 
protractor for measuring, 79. 

Denebola in Leo, the Lion, 177. 

Dial of mariner's compass, 79. 

Diameter defined, 194. 

Difference between true North Pole 
and magnetic North Pole, 
88. 

Dipping needle, how to make a, 
79. 

Dog Star, 8. 

Double stars, 204. 

Earth, 47, 54. 

cross section of, 67. 

divided into degrees, 81. 

divided into standard meridians, 
158. 

from the Moon, view of, 104. 

a great magnet, 77. 

in the making, 66. 

Moon eclipsed by, 107. 

and Moon joined together, 89. 

orbit of, an ellipse, 70. 

precession of the, 173. 

proof it is round, 67. 

shadow of, 109. 

thickness of air ground, 125. 

tilts on its axis, 69. 

travels round the Sun, 70. 

turning of, makes day and night, 
69. 

turning in orbit makes the sea- 
sons, 72. 

turns on its axis, proof that, 68. 

umbra of, 135. 

when cooled off, 66. 
Earth-shine, 93. 
Eastern time, 158. 
Eclipse, annular of the Sun, 112. 



Eclipse, defined, 113, 194, 195. 
of the Moon, 107. 
partial, of the Sun, 112. 
seeing an, 107. 
of the Sun by Moon, 110. 
for next 30 years, 112. 
total, of the Sun, 112. 
Ecliptic, the, 46, 69, 72, 170. 
Ellipse, 113. 

Ellis seasonal twilight chart, 201. 
Epsilon in Lyra through a glass, 

150. 
Equation of time, 155, 207. 
Equator, crossing the ecliptic, 
72. 
defined, 194. 
Equinox, autumnal, 178. 

vernal, 178. 
Ether, what it is, 123, 125, 127. 
Evening star, Venus, 50. 
Experiment, Foucault's pendulum, 
68. 
in centrifugal force, 90. 
making star trails, 68. 
showing, eclipse of Sun, 110. 
how Moon cracked, 145. 
Moon eclipsed by Earth, 107. 
Moon's crescent, 95. 
Moon's day and year, 94. 
Moon's phases, 98. 
reflection of light, 131. 
refraction of light, 132. 
with a bell, 125. 
with candle to show the seasons, 

73. 
with cardboard zodiac, 170. 
with spinning top, 72. 
with water waves, 124. 
Eye, a camera, 127. 
how it sees, 127. 
human, 8. 
light and, 129. 
Eyesight, star tests for, 197. 



224 



INDEX 



Finding, the North Star, 2. 
the North with Pegasus, 19. 

Fireballs, 116. 

First magnitude stars, 200. 

Fixed stars, 7. 

Flying Horse, constellation of, 19. 

Focal length of a lense, 134. 

Focus of lens, 133. 

Forecasting the weather by ba- 
rometer, 35. 

Forecasting weather by signs, 36. 

Foucault 's pendulum experiment, 
68. 

Fraunhofer's lines, 190. 

Frequency of vibrating atoms, 123. 

Friction, 60. 

Gemini, the Twins, constellation of, 
63, 176. 

Geometrical figures, 195. 

Gibbous Moon, 93. 

Girl in the Moon, 147. 

Gravitation defined, 59. 

Great Bear, 5. 

Great Square of Pegasus, constel- 
lation of, 17. 

Greek alphabet, 197. 

Greenwich time, 86. 

Grimaldi on the Moon, 94, 147. 

Guardian stars of the Little Dip- 
per, 16. 

Handbook of Boy Scouts, 193. 
Harvest and Hunter's Moon, 98. 
Heat, how it travels, 123. 
Heat, what it is, 122, 129. 
Heliograph, how to make and use 

a, 40, 41. 
Horizon, a good, 153. 
Horizon glass, 84. 
Horizontal line defined, 194. 
Horoscopes, astrologer's, 180. 
Horse and Eider, 11. 



Hours, dividing a circle into, 157. 
How a camera is made, 185. 
How the cave man marked time, 

152. 
How the eye sees, 127. 
How to find, Aries, the Earn, 174. 

a comet, 113. 

constellations of the Zodiac, 169. 

focus of a lens, 133. 

longitude 86. 

the North Star, 83. 

with dipping needle and pro- 
tractor, 82. 
with sticks and pail of water, 
83. 

power of a telescope, 143. 
How to get Sun time, 153. 
How to know, the stars, 14. 

you are at the North Pole, 87. 
How to look at the Sun, 148. 
How to make, a cheap telescope, 
140. 

pinhole telescope, 138. 

simple compass, 77. 

simple dipping needle, 79. 

star finder, 1. 

star trails, 187. 
How the Moon makes the tides, 99. 
How a photograph is made, 185. 
How a prism bends light, 133. 
How to read the almanac, 182. 
How a spectroscope is made, 191. 
How the stars shine, 121. 
How the stars were made, 119. 
How a telescope works, 139. 
How to tell, time by the Big Dip- 
per, 12. 

a true meteorite, 117. 
How time is sent, by telegraph, 
163. 

by wireless, 165. 
How to use a prism, 188. 
How we see light, 126. 



INDEX 



225 



Hyades in Taurus, 175. 
Hyperboles, 113. 

Imaginary Sun time, 155. 
Index mirror, 84. 
Invisible stars 206. 

Jupiter, 47, 61. 
nine moons of, 52. 
seeing, 51. 
through a telescope, 149. 

Kullmer star finder, 209. 

Latitude, how to find, by protrac- 
tion and dipping needle, 82. 

with sextant, 84. 

with sticks and pail of water, 83^ 
Lens, concave, 134. 

convex, 133. 

how to find focus of a, 133. 
Leo, the Lion, 177. 
Libra, the Balance, 178. 
Light, denned, 122. 

how made, 122. 

how it passes through glass, 130. 

how it travels, 123. 

how we see it, 126, 129. 

reflection of, 131, 132. 

refraction of, 132. 

speed of, 188. 

what makes the colors in, 123. 

wave lengths of, 123, 130. 
Little Bear, constellation of, 16. 
Little Dipper, constellation of, 15. 
Local time, 86, 155. 
Longitude, how to find it, 86. 

meridians of, 86. 

use of sextant to find, 84. 
Lyra, the Lyre, 201. 

Magellan 's voyage, 67. 
Magnet, Earth a great, 77. 



Magnet, steel-bar, 76. 
Magnetic lines of force, 76. 
Magnetic North Pole and true 

North Pole, 76, 88. 
Magnetic storms, 34. 
Magnitude of stars, 199. 
Man in the Moon, 93. 
Mariner 's compass, 78. 
Mars, 47, 49. 

is it peopled! 49. 

through a telescope, 149. 
Mean length, defined, 154. 
Mean solar time, 154. 
Mean time, 152. 
Mercury, 47, 48, 61. 

phases of, 48. 

through a telescope, 148. 
Meridian defined, 18. 

prime, 156. 

your, 61. 

zero, 156. 
Meridians, fixed, 157. 

of longitude, 85. 

standard, 86, 156. 
Meteorites, kinds of, 117. 

tests for, 117. 
Meteors, and meteorites, 116. 

orbits of, 116. 
Merit badge for star-craft, 193. 
Milk dipper in the Milky Way, 

181. 
Milky Way, stars of the, 117, 118. 

through a glass, 150. 
Mizar in the Big Dipper, 11, 150. 
Moon, 89. 

Apennines on the, 146. 

aspects of the, 94. 

Copernicus on the, 148. 

crescent, 93. 

day and year of the, 94. 

and Earth joined together, 89. 

eclipse of the, 107. 

eclipse of Sun by the, 110. 



INDEX 



Moon, gibbous, 93. 

Grimaldi on the, 94, 147. 

Harvest and Hunter's, 99. 

how it cracked, 144. 

if you were on it, 101. 

imitating volcanoes on the, 91. 

Man in the, 93. 

motions of the, 94. 

old, in the new Moon's arms, 
93. 

other things about the, 106. 

phases of the, how made, 94, 95, 
96. 

photographing the, 188. 

seas on the, 144. 

seeing the, with the naked eye, 
92. 

telling time by the, 105. 

through a telescope, 144. 

time marked by the, 151. 

a trip to the, 101. 

Tycho on the, 144. 

volcanoes on the, 91. 

weather, and the, 105. 

where it came from, 90. 
Moon-girl, 146. 
Morning star, Venus, 50. 
Morse Code, 39. 
Motions of the Moon, 94. 
Mountain time, 160. 

Naked eye aids, 139. 

Naked eye view of the Moon, 93. 

Nebula, 114, 118. 

of Orion, great, 119. 
Nebular hypothesis, 119. 
Nebule, different forms of, 119. 
Neptune, the oiltpost planet, 47, 
53. 

seeing, 53. 

through a telescope, 149. 
North, to find, by a watch, 45. 
with Capella, 24. 



North, with Orion, 23. 
with Pegasus, 19. 
North magnetic pole, 76. 
North Pole, 8. 

explorers at the, 87. 

how to know you are at, 87. 

shadows at, 88. 

true, and magnetic North Pole, 
76, 88. 
North Star, 1, 2, 4. 

how to find, 1, 2. 

how to find latitude of, 83. 

sighting the, 2. 

through a glass, 150. 
Northern Cross, 202. 
Northern Lights, 34. 

Old Farmers' Almanac, 184. 

Old Moon in the new Moon 's arms, 

93. 
Opera glasses, 140. 
Optic nerve, 126. 
Orion, of the Arabians, 22. 

belt of stars of, 21. 

constellation of, 20. 

finding the North with, 23. 

the Great Hunter, 20. 

Great Nebula of, 119. 

sword of stars of, 22. 

Pacific time, 160. 
Paraboles, 113. 

Partial eclipse of the Sun, 112. 
Pegasus, the Flying Horse, 19. 
Pendulum illustrating Sun's at- 
traction, 59. 
Penumbra, 135. 

Perpendicular line defined, 194. 
Phases, of Mercury, 48. 

of Venus, 50. 
Photograph, how made, 185. 
Photographing the Moon, 188. 

the stars, 185. 



INDEX 



227 



Photographing the Sun, 187. 
Photosphere of the Sun, 32. 
Pinhole sunshade, 30. 
Pinhole telescope, 30, 138. 
Pisces, the Fishes, constellation of, 

63, 174. 
Plane, defined, 55. 
Planet, how to plot position of a, 

61. 
Planetesimal hypothesis, 119, 120. 
Planets, eggshell experiment to 
show motions of, 57. 

first aid to remembering, 57. 

how held in space, 57. 

how to know the, 47. 

names and sizes of, 47. 

path of, 170. 

plane of, 55. 

round the Sun, position of, 
54. 

the Sun's kiddies, 46. 

through a telescope, 148. 

use of almanac for finding, 61. 

why they spin, 60. 
Pleiades, in Taurus, 26. 

through a glass, 150. 
Plotting the position of a planet, 

61. 
Plough, the, 5. 
Pointer stars of the Big Dipper, 

10. 
Polar nights, 71. 
Polaris, the Pole Star, 4. 
Pole Star, the, 4, 8. 
Precession of the Earth, 173. 
Prime meridian, 156. 
Prism, 132. 

forming a spectrum, 134. 

how to use, 188. 
Produce, defined, 8. 
Prominences of the Sun, 31. 
Protractor, showing degrees, 81. 

showing degrees latitude, 82. 



Eadius defined, 194. 
Eailroad time, 156. 
Eeflection of light, 131. 
Eegulus in Leo, the Lion, 177. 
Eigel in Orion, 28. 
Eight angle defined, 194. 
Eing defined, 194. 

Sagittarius, the Archer, 180. 
Saturn, 47. 

seeing, 52. 

through a telescope, 149. 
Scorpius, the Scorpion, 180. 
Seasonal twilight chart, Ellis, 201. 
Seasons: autumn, 74. 

spring, 74. 

summer, 75. 

winter, 74. 

cycle of the, 75. 

Earth turning round Sun makes 
the, 72. 

experiment to show the, 73. 
Seeing, an eclipse, 107. 

the Moon with naked eye, 92. 

the stars, 121. 
Sextant, how to use it, 84. 
Shadow of, the Earth, 109. 

the Penumbra, 135. 

the Umbra, 135. 
Shadows, 135. 

at the North Pole, 88. 
Shooting the Sun, 84. 
Shooting stars, 116. 
Sighting the North Star, 2. 
Signalling with the Sun 's rays, 38. 
Signs, in the almanac, 183. 

of the Zodiac, 168. 
Sirius, the Dog Star, 8, 118. 
Sky, things in the, 107. 
Smoked Sun glasses, 30. 
Solar day, 154. 

apparent, 154. 
Solar noon, 153. 



228 



INDEX 



Solar spectrum, 189. 

Solar system, in perspective, 56. 

top view of, 55. 
Solar time, 152. 

mean, 154. 
Solstice, summer, 176. 

winter, 181. 
Sound waves, 125. 
South Pole, 26. 
Spectroscope, 189. 

how made, 191. 
Spectrum, 133. 

solar, 189. 
-Spring, 74. 
Spyglass, 136. 

stars seen through, 144. 
Standard meridians, 86, 156. 
Standard time, 155. 

zone system of, 156. 
Standard time meridians in United 

States, 159. 
Star-craft, merit badge for, 193. 
•Star finder, how to make a, 1. 

Kullmer, 209. 
Star tests for eyesight, 197. 
Star time, 160. 
Star trails, how to make, 187. 
Stars, colored, 202. 

constellations having first mag- 
nitude, 201. 

double, 204. 

first magnitude, 200. 

how made, 119. 

bow they shine, 121. 

invisible or dark, 206. 

magnitude "of, 199. 

near the Sun's path, 62. 

photographing, 185. 

seeing, 121. 

through a telescope, 149. 

variable, 205. 

what they are made of, 188. 

of the Zodiac, 166. 



Straight line denned, 194. 

Summer, 75. 

Summer solstice, 176. 

Sun, annular eclipse of the, 87. 

arctic, 87. 

attraction of, illustrated, 59. 

brightest star, 29. 

burning gases of, 121. 

chromosphere of, 32. 

core of, 32. 

corona of, 33. 

cross section of, 34. 

eclipse of, by the Moon, 110. 

how to see, 29. 

layers of flame of, 31. 

lighting a fire with, 37. 

from the Moon, view of, 104. 
stars near the, 62. 

partial eclipse of the, 112. 

path of the, 46, 170. 

photographing the, 187. 

photosphere of, 32. 

positions of planets round the, 
54. 

prominences of, 31. 

rays of, signalling with, 38. 

shooting the, 84. 

surface of, 32. 

time marked by, 151. 

through a telescope, 148. 

weather and, 34. 

what it is made of, 30. 
Sun dial, how to make a simple, 

42. 
Sun spots, 31. 

effects of, on the Earth, 33. 
Sun time, 152. 

how to set, 153. 

imaginary, 155. 
Sword of Orion, 22. 

Tangent denned, 58, 194. 
Taurus, Aldebaran in, 26. 



INDEX 



Taurus, constellation of, 24, 63, 175. 

of the Egyptians, 26. 
Telescope, 136. 

astronomical, 138. 

with convex lenses, 142. 

denned, 136. 

discovery of, 136. 

equatorial, 188. 

how to make a cheap, 140. 

how to make a pinhole, 138. 

how it works, 139. 

kinds of, 137, 139. 

magnifying power of, 143. 

Mars through a, 149. 

Mercury through a, 148. 

Moon through a, 144. 

Neptune through a, 149. 

opera glass, 141. 

pinhole, 30. 

planets through a, 148. 

Saturn through a, 149. 

seeing the stars through a, 144. 

of sextant, 84. 

simple, 140. 

stars through a, 149. 

Sun through a, 148. 

Uranus through a, 149. 

Venus through a, 148. 
Telescope lens, mounting for, 140. 
Test for eyesight, Alcor, 11. 
Tides, high and low, 100. 

how the Moon makes, 99. 

spring and neap, 101. 
Time, apparent, 152. 

at different cities, 161. 

by the Moon, telling, 105. 

by the stars, 160. 

central, 160. 

to change star, into solar, 163. 

correct, 161. 

how obtained, 162. 

distributed by telegraph, 161. 
by wireless, 161. 



Time, eastern, 158. 

equation of, 155, 207. 

Greenwich, 86. 

how sent by telegraph, 163. 

how to tell, by the Big Dipper, 
12. 

imaginary Sun, 155. 

local, 86, 155. 

marked by the Moon, 151. 
by the Sun, 151. 

mean, 152. 
solar, 154. 

mountain, 160. 

o' day, 151. 

Pacific, 160. 

railroad, 156. 

standard, 155. 

Sun, 154. 

what is it? 151. 

zone system of standard, 156. 
Time ball, how made and worked, 

164. 
Time meridians in United States, 

standard, 159 
Total eclipse of the Sun, 110. 
Transit of a star, 162. 
Transit instrument, 162. 
Trapezium defined, 20, 21. 
True North Pole, 76. 
Tycho on the Moon, 144. 

Umbra of the Moon, 135. 
Uranus, HerschePs planet, 47, 53. 

seeing, 53. 

through a telescope, 149. 
Ursa Major, constellation of, 6. 
Ursa Minor, constellation of, 16. 

Vanishing Man in the Moon, 146. 
Variable stars, 205. 
Venus, 47, 61. 

phases of, 50. 

seeing, 50. 



230 



INDEX 



Venus, through a telescope, 148. 
Vernal equinox, 178. 
Vertical line denned, 194. 
Vesta, an asteroid, 54. 
Vibrating atoms, 123. 
Vibrations of bell, number of, 125. 
Virgo, the Virgin, 177. 
Volcanoes, how they were made, 
91. 
on the Moon, 91. 

Waves, air, 125. 

in the ether, 127. 

length of light, 123. 

sound, 125. 

speed of, 126. 

of water, experiment with, 124. 
Weather, forecasting, by the ba- 
rometer, 35. 

by signs, 37. 



Weather, and the Mood 105. 

Sun and the, 34. 
Winter, 74. 
Winter solstice, 181. 
Wireless, time distributed by, 161. 
Wireless receiving sets, 165. 

Zero meridian, 156. 
Zodiac, as invented by the ancients, 
167. 
as we know it today, 167. 
constellations of, 168. 
experiment with a cardboard, 

170. 
how to find the constellations 

of the, 169. 
signs of the, 168. 
stars of the, 166. 
what it is, 166. 
Zone system of standard time, 156. 



(I) 



